MFS Series Trust I - MFS Value Fund NCSRS Certified semi-annual shareholder report (management investment company)

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM N-CSR

CERTIFIED SHAREHOLDER REPORT OF

REGISTERED MANAGEMENT INVESTMENT COMPANIES

Investment Company Act file number 811-04777

MFS SERIES TRUST I

(Exact name of registrant as specified in charter)

111 Huntington Avenue, Boston, Massachusetts 02199

(Address of principal executive offices) (Zip code)

Christopher R. Bohane

Massachusetts Financial Services Company

111 Huntington Avenue

Boston, Massachusetts 02199

(Name and address of agents for service)

Registrant’s telephone number, including area code: (617) 954-5000

Date of fiscal year end: August 31

Date of reporting period: February 28, 2018

ITEM 1.

REPORTS TO STOCKHOLDERS.

Semiannual Report

February 28, 2018

LOGO

MFS® Core Equity Fund

LOGO

RGI-SEM

MFS® Core Equity Fund

CONTENTS


Letter from the Executive Chairman			1
Portfolio composition			2
Expense table			3
Portfolio of investments			5
Statement of assets and liabilities			13
Statement of operations			15
Statements of changes in net assets			16
Financial highlights			17
Notes to financial statements			27
Proxy voting policies and information			40
Quarterly portfolio disclosure			40
Further information			40
Information about fund contracts and legal claims			41
Provision of financial reports and summary prospectuses			41
Contact information back cover

The report is prepared for the general information of shareholders.

It is authorized for distribution to prospective investors only when preceded or accompanied by a current prospectus.

NOT FDIC INSURED • MAY LOSE VALUE • NO BANK GUARANTEE

LOGO

LETTER FROM THE EXECUTIVE CHAIRMAN

Dear Shareholders:

Rising bond yields have led to a measurable uptick in market volatility — a departure from the low-volatility environment that prevailed for much of 2017. In spite of this,

global markets remain elevated amid synchronized economic growth. Although the U.S. Federal Reserve continues to gradually raise interest rates and shrink its balance sheet, monetary policy remains accommodative around the world, with many central banks taking only tentative steps toward tighter policies.

Newly enacted U.S. tax reforms have been welcomed by equity markets, while emerging market economies have benefited from a weaker U.S. dollar. Around the world, inflation remains largely subdued, but tight labor markets and solid global demand have investors on the lookout for its potential resurgence. Increased

U.S. protectionism is also a growing concern, as investors fear that trade friction could disrupt the synchronized uptick in global growth.

At MFS®, we believe having a disciplined, long-term investment approach through a full market cycle is essential to capturing the best opportunities while also managing risk. In our view, such a strategy, along with the professional guidance of a financial advisor, will help you reach your investment objectives.

Respectfully,

LOGO

Robert J. Manning

Executive Chairman

MFS Investment Management

April 13, 2018

The opinions expressed in this letter are subject to change and may not be relied upon for investment advice. No forecasts can be guaranteed.

PORTFOLIO COMPOSITION

Portfolio structure

LOGO


Top ten holdings
Alphabet, Inc., “A”			2.5%
Amazon.com, Inc.			2.5%
Bank of America Corp.			2.5%
Facebook, Inc., “A”			2.5%
Citigroup, Inc.			2.2%
American Tower Corp., REIT			2.0%
Chevron Corp.			1.9%
Analog Devices, Inc.			1.9%
Texas Instruments, Inc.			1.7%
Pfizer, Inc.			1.7%


Equity sectors
Technology			19.6%
Financial Services			19.2%
Health Care			12.8%
Industrial Goods & Services			8.9%
Retailing			6.8%
Consumer Staples			5.7%
Utilities & Communications (s)			5.4%
Leisure			4.8%
Special Products & Services			4.8%
Energy			4.8%
Basic Materials			3.5%
Transportation			1.2%
Autos & Housing			1.2%

(s)	Includes securities sold short.

Cash & Cash Equivalents includes any cash, investments in money market funds, short-term securities, and other assets less liabilities. Please see the Statement of Assets and Liabilities for additional information related to the fund’s cash position and other assets and liabilities.

Percentages are based on net assets as of February 28, 2018.

The portfolio is actively managed and current holdings may be different.

EXPENSE TABLE

Fund expenses borne by the shareholders during the period, September 1, 2017 through February 28, 2018

As a shareholder of the fund, you incur two types of costs: (1) transaction costs, including sales charges (loads) on certain purchase or redemption payments, and (2) ongoing costs, including management fees; distribution and service (12b-1) fees; and other fund expenses. This example is intended to help you understand your ongoing costs (in dollars) of investing in the fund and to compare these costs with the ongoing costs of investing in other mutual funds.

The example is based on an investment of $1,000 invested at the beginning of the period and held for the entire period September 1, 2017 through February 28, 2018.

Actual Expenses

The first line for each share class in the following table provides information about actual account values and actual expenses. You may use the information in this line, together with the amount you invested, to estimate the expenses that you paid over the period. Simply divide your account value by $1,000 (for example, an $8,600 account value divided by $1,000 = 8.6), then multiply the result by the number in the first line under the heading entitled “Expenses Paid During Period” to estimate the expenses you paid on your account during this period.

Hypothetical Example for Comparison Purposes

The second line for each share class in the following table provides information about hypothetical account values and hypothetical expenses based on the fund’s actual expense ratio and an assumed rate of return of 5% per year before expenses, which is not the fund’s actual return. The hypothetical account values and expenses may not be used to estimate the actual ending account balance or expenses you paid for the period. You may use this information to compare the ongoing costs of investing in the fund and other funds. To do so, compare this 5% hypothetical example with the 5% hypothetical examples that appear in the shareholder reports of the other funds.

Please note that the expenses shown in the table are meant to highlight your ongoing costs only and do not reflect any transactional costs, such as sales charges (loads). Therefore, the second line for each share class in the table is useful in comparing ongoing costs only, and will not help you determine the relative total costs of owning different funds. In addition, if these transactional costs were included, your costs would have been higher.

Expense Table – continued


Share Class		Annualized Expense Ratio		Beginning Account Value 9/01/17		Ending Account Value 2/28/18		Expenses Paid During Period (p) 9/01/17-2/28/18
A	Actual		0.99%		$1,000.00		$1,104.21		$5.17
A	Hypothetical (h)		0.99%		$1,000.00		$1,019.89		$4.96
B	Actual		1.74%		$1,000.00		$1,100.18		$9.06
B	Hypothetical (h)		1.74%		$1,000.00		$1,016.17		$8.70
C	Actual		1.74%		$1,000.00		$1,100.13		$9.06
C	Hypothetical (h)		1.74%		$1,000.00		$1,016.17		$8.70
I	Actual		0.74%		$1,000.00		$1,105.60		$3.86
I	Hypothetical (h)		0.74%		$1,000.00		$1,021.12		$3.71
R1	Actual		1.74%		$1,000.00		$1,100.21		$9.06
R1	Hypothetical (h)		1.74%		$1,000.00		$1,016.17		$8.70
R2	Actual		1.24%		$1,000.00		$1,102.83		$6.47
R2	Hypothetical (h)		1.24%		$1,000.00		$1,018.65		$6.21
R3	Actual		0.99%		$1,000.00		$1,104.19		$5.17
R3	Hypothetical (h)		0.99%		$1,000.00		$1,019.89		$4.96
R4	Actual		0.74%		$1,000.00		$1,105.64		$3.86
R4	Hypothetical (h)		0.74%		$1,000.00		$1,021.12		$3.71
R6	Actual		0.67%		$1,000.00		$1,106.13		$3.50
R6	Hypothetical (h)		0.67%		$1,000.00		$1,021.47		$3.36

(h)	5% class return per year before expenses.

(p)

“Expenses Paid During Period” are equal to each class’s annualized expense ratio, as shown above, multiplied by the average account value over the period, multiplied by 181/365 (to reflect the one-half year period). Expenses paid do not include any applicable sales charges (loads). If these transaction costs had been included, your costs would have been higher.

Notes to Expense Table

Expense ratios include 0.01% of investment related expenses from short sales (See Note 2 of the Notes to Financial Statements). Each class with a Rule 12b-1 service fee is subject to a rebate of a portion of such fee. Such rebates are included in the expense ratios above. For Class A shares, this rebate reduced the expense ratio above by 0.01%. See Note 3 in the Notes to Financial Statements for additional information.

PORTFOLIO OF INVESTMENTS

2/28/18 (unaudited)

The Portfolio of Investments is a complete list of all securities owned by your fund. It is categorized by broad-based asset classes.


Common Stocks - 99.0%
Issuer	Shares/Par		Value ($)
Aerospace - 3.8%
Boeing Co.		24,736	$	8,959,626
CACI International, Inc., “A” (a)		30,887		4,603,707
Curtiss-Wright Corp.		32,499		4,386,715
FLIR Systems, Inc.		117,290		5,758,939
Honeywell International, Inc.		113,489		17,149,323
Northrop Grumman Corp.		39,048		13,668,362
Textron, Inc.		91,379		5,469,033
United Technologies Corp.		92,936		12,522,197

			$	72,517,902
Alcoholic Beverages - 0.4%
Constellation Brands, Inc., “A”		36,756	$	7,920,183

Apparel Manufacturers - 1.4%
Hanesbrands, Inc.		294,166	$	5,706,820
NIKE, Inc., “B”		320,115		21,457,309

			$	27,164,129
Automotive - 0.7%
Aptiv PLC		82,392	$	7,524,862
CoPart, Inc. (a)		107,393		5,027,066

			$	12,551,928
Biotechnology - 1.4%
Biogen, Inc. (a)		66,387	$	19,185,179
Incyte Corp. (a)		97,996		8,345,339

			$	27,530,518
Brokerage & Asset Managers - 1.5%
Blackstone Group LP		364,896	$	12,406,464
TD Ameritrade Holding Corp.		151,341		8,702,108
TMX Group Ltd.		138,767		8,295,524

			$	29,404,096
Business Services - 3.1%
Amdocs Ltd.		55,307	$	3,638,647
Cognizant Technology Solutions Corp., “A”		122,064		10,011,689
Cotiviti Holdings, Inc. (a)		67,737		2,269,867
DXC Technology Co.		86,647		8,884,783
Fidelity National Information Services, Inc.		102,933		10,003,029

Portfolio of Investments (unaudited) – continued


Issuer	Shares/Par		Value ($)
Common Stocks - continued
Business Services - continued
First Data Corp. (a)		44,268	$	691,466
Global Payments, Inc.		76,040		8,622,176
Grand Canyon Education, Inc. (a)		23,201		2,277,178
Total System Services, Inc.		43,428		3,819,493
Verisk Analytics, Inc., “A” (a)		58,489		5,976,991
Zendesk, Inc. (a)		77,139		3,330,862

			$	59,526,181
Cable TV - 0.9%
Altice USA, Inc. (a)(l)		108,007	$	1,965,727
Comcast Corp., “A”		411,145		14,887,561

			$	16,853,288
Chemicals - 2.3%
Celanese Corp.		51,787	$	5,223,237
CF Industries Holdings, Inc.		144,679		5,966,562
DowDuPont, Inc.		181,749		12,776,954
Ingevity Corp. (a)		69,469		5,203,923
PPG Industries, Inc.		123,729		13,912,089

			$	43,082,765
Computer Software - 4.6%
8x8, Inc. (a)		344,932	$	6,295,009
Adobe Systems, Inc. (a)		120,776		25,257,885
Microsoft Corp.		297,018		27,851,378
Salesforce.com, Inc. (a)		240,096		27,911,160

			$	87,315,432
Computer Software - Systems - 1.7%
Apple, Inc.		100,825	$	17,958,949
Rapid7, Inc. (a)		253,320		6,690,181
SS&C Technologies Holdings, Inc.		90,582		4,485,621
Switch, Inc.		42,829		591,468
Xerox Corp.		100,600		3,050,192

			$	32,776,411
Construction - 0.5%
Sherwin-Williams Co.		24,048	$	9,657,196

Consumer Products - 1.7%
Coty, Inc., “A”		386,557	$	7,468,281
Estee Lauder Cos., Inc., “A”		65,061		9,007,045
Newell Brands, Inc.		168,228		4,321,777
Procter & Gamble Co.		148,323		11,646,322

			$	32,443,425

Portfolio of Investments (unaudited) – continued


Issuer	Shares/Par		Value ($)
Common Stocks - continued
Consumer Services - 1.7%
Bookings Holdings, Inc. (a)		9,909	$	20,155,302
Bright Horizons Family Solutions, Inc. (a)		72,063		6,887,061
ServiceMaster Global Holdings, Inc. (a)		86,529		4,444,130

			$	31,486,493
Containers - 0.6%
Berry Global Group, Inc. (a)		116,412	$	6,332,813
Graphic Packaging Holding Co.		107,662		1,648,305
Sealed Air Corp.		93,713		3,970,620

			$	11,951,738
Electrical Equipment - 2.7%
AMETEK, Inc.		177,382	$	13,434,913
AZZ, Inc.		87,596		3,578,297
HD Supply Holdings, Inc. (a)		187,049		6,780,526
Johnson Controls International PLC		243,975		8,995,358
Sensata Technologies Holding B.V. (a)		171,584		9,069,930
TE Connectivity Ltd.		63,998		6,597,554
WESCO International, Inc. (a)		49,998		3,112,375

			$	51,568,953
Electronics - 6.6%
Analog Devices, Inc.		391,204	$	35,267,040
Applied Materials, Inc.		151,354		8,716,477
Broadcom Corp.		69,621		17,158,792
Inphi Corp. (a)		174,541		4,843,513
Mellanox Technologies Ltd. (a)		82,108		5,649,030
NVIDIA Corp.		93,244		22,565,048
Texas Instruments, Inc.		294,649		31,925,219

			$	126,125,119
Energy - Independent - 2.1%
Concho Resources, Inc. (a)		44,931	$	6,775,595
Energen Corp. (a)		27,057		1,480,288
EOG Resources, Inc.		130,967		13,282,673
EQT Corp.		27,832		1,400,228
Hess Corp.		150,802		6,849,427
Marathon Petroleum Corp.		125,849		8,061,887
Parsley Energy, Inc., “A” (a)		79,185		2,001,797

			$	39,851,895
Energy - Integrated - 1.9%
Chevron Corp. (s)		316,531	$	35,426,149

Portfolio of Investments (unaudited) – continued


Issuer	Shares/Par		Value ($)
Common Stocks - continued
Engineering - Construction - 0.2%
KBR, Inc.		226,424	$	3,428,059

Entertainment - 1.3%
Six Flags Entertainment Corp.		88,491	$	5,671,388
Time Warner, Inc.		148,493		13,803,909
Twenty-First Century Fox, Inc.		129,753		4,777,506

			$	24,252,803
Food & Beverages - 2.7%
Blue Buffalo Pet Products, Inc. (a)		63,253	$	2,533,915
Cal-Maine Foods, Inc. (a)		137,023		5,837,180
J.M. Smucker Co.		34,413		4,346,362
Mondelez International, Inc.		256,777		11,272,510
Monster Worldwide, Inc. (a)		134,639		8,532,074
PepsiCo, Inc.		163,685		17,961,155
TreeHouse Foods, Inc. (a)		21,102		802,298

			$	51,285,494
Gaming & Lodging - 0.4%
Marriott International, Inc., “A”		48,295	$	6,819,737

General Merchandise - 0.4%
Dollar Tree, Inc. (a)		67,989	$	6,978,391

Health Maintenance Organizations - 1.5%
Cigna Corp.		93,956	$	18,405,041
Humana Inc.		38,432		10,446,586

			$	28,851,627
Insurance - 3.0%
Aon PLC		199,931	$	28,054,318
Chubb Ltd.		99,299		14,092,514
Hartford Financial Services Group, Inc.		267,686		14,147,205

			$	56,294,037
Internet - 5.7%
Alphabet, Inc., “A” (a)(s)		43,287	$	47,785,385
Facebook, Inc., “A” (a)		263,594		47,004,082
LogMeIn, Inc.		118,844		13,732,424

			$	108,521,891
Leisure & Toys - 0.5%
Electronic Arts, Inc. (a)		80,166	$	9,916,534

Portfolio of Investments (unaudited) – continued


Issuer	Shares/Par		Value ($)
Common Stocks - continued
Machinery & Tools - 1.7%
Illinois Tool Works, Inc.		40,372	$	6,517,656
IPG Photonics Corp. (a)		16,378		4,023,092
ITT, Inc.		101,562		5,096,381
Roper Technologies, Inc.		40,428		11,121,339
SPX FLOW, Inc. (a)		112,157		5,468,775

			$	32,227,243
Major Banks - 4.0%
Bank of America Corp.		1,472,181	$	47,257,010
Morgan Stanley		194,514		10,896,674
PNC Financial Services Group, Inc.		107,950		17,019,397

			$	75,173,081
Medical & Health Technology & Services - 1.0%
HCA Healthcare, Inc.		50,778	$	5,039,717
Henry Schein, Inc. (a)		25,217		1,669,113
ICON PLC (a)		22,955		2,601,031
McKesson Corp.		60,484		9,026,027

			$	18,335,888
Medical Equipment - 3.2%
Abiomed, Inc. (a)		13,762	$	3,690,693
Align Technology, Inc. (a)		13,478		3,538,244
Danaher Corp.		61,138		5,978,074
Edwards Lifesciences Corp. (a)		104,697		13,994,848
Medtronic PLC		234,422		18,727,974
PerkinElmer, Inc.		100,258		7,653,696
Steris PLC		77,135		7,042,425

			$	60,625,954
Metals & Mining - 0.3%
First Quantum Minerals Ltd.		135,228	$	2,203,567
Teck Resources Ltd., “B”		132,030		3,773,418

			$	5,976,985
Natural Gas - Distribution - 0.0%
Sempra Energy		8,000	$	871,840

Natural Gas - Pipeline - 0.5%
Cheniere Energy, Inc. (a)		152,557	$	8,012,294
Enterprise Products Partners LP		58,703		1,492,230

			$	9,504,524
Network & Telecom - 1.0%
Cisco Systems, Inc.		408,093	$	18,274,405

Portfolio of Investments (unaudited) – continued


Issuer	Shares/Par		Value ($)
Common Stocks - continued
Oil Services - 0.8%
Liberty Oilfield Services, Inc. (a)		160,509	$	2,983,862
Patterson-UTI Energy, Inc.		462,116		8,350,436
Schlumberger Ltd.		63,613		4,175,558

			$	15,509,856
Other Banks & Diversified Financials - 7.7%
Bank of the Ozarks, Inc.		160,126	$	7,988,686
Citigroup, Inc. (s)		551,254		41,614,165
Discover Financial Services		150,459		11,860,683
EuroDekania Ltd. (u)		580,280		69,024
First Republic Bank		49,279		4,573,091
Northern Trust Corp.		74,085		7,843,379
U.S. Bancorp		451,955		24,568,274
Visa, Inc., “A”		224,176		27,560,197
Wintrust Financial Corp.		133,386		11,272,451
Zions Bancorporation		155,696		8,558,609

			$	145,908,559
Pharmaceuticals - 5.7%
Bristol-Myers Squibb Co.		291,224	$	19,279,029
Eli Lilly & Co.		147,143		11,332,954
Johnson & Johnson		210,226		27,304,153
Pfizer, Inc.		871,422		31,641,333
Zoetis, Inc.		226,873		18,344,950

			$	107,902,419
Pollution Control - 0.4%
Clean Harbors, Inc. (a)		63,334	$	3,162,267
Waste Connections, Inc.		74,957		5,305,456

			$	8,467,723
Railroad & Shipping - 1.2%
Canadian Pacific Railway Ltd.		62,984	$	11,250,832
Kansas City Southern Co.		49,737		5,124,900
Union Pacific Corp.		55,103		7,177,166

			$	23,552,898
Real Estate - 3.1%
Gramercy Property Trust, REIT		314,862	$	6,816,762
Life Storage, Inc., REIT		134,850		10,593,816
Medical Properties Trust, Inc., REIT		1,725,204		21,151,001
Store Capital Corp., REIT		490,249		11,687,536
Sun Communities, Inc., REIT		51,635		4,521,161
Washington Prime Group, Inc., REIT		592,138		3,878,504

			$	58,648,780

Portfolio of Investments (unaudited) – continued


Issuer	Shares/Par		Value ($)
Common Stocks - continued
Restaurants - 1.8%
Aramark		153,142	$	6,387,553
Dave & Buster’s, Inc. (a)		84,638		3,789,243
Starbucks Corp.		308,695		17,626,485
U.S. Foods Holding Corp. (a)		179,300		5,986,827

			$	33,790,108
Specialty Chemicals - 0.3%
Univar, Inc. (a)		174,265	$	5,020,575

Specialty Stores - 5.0%
Amazon.com, Inc. (a)		31,389	$	47,474,293
Costco Wholesale Corp.		61,470		11,734,623
L Brands, Inc.		141,611		6,985,671
Michaels Co., Inc. (a)		207,752		4,780,374
TJX Cos., Inc.		131,116		10,840,671
Tractor Supply Co.		113,970		7,400,072
Urban Outfitters, Inc. (a)		173,674		6,128,955

			$	95,344,659
Telecommunications - Wireless - 2.0%
American Tower Corp., REIT		272,717	$	37,997,660

Telephone Services - 0.5%
Verizon Communications, Inc.		205,240	$	9,798,158

Tobacco - 0.9%
Philip Morris International, Inc.		168,442	$	17,442,169

Utilities - Electric Power - 2.6%
Alliant Energy Corp.		58,330	$	2,254,454
American Electric Power Co., Inc.		106,609		6,991,418
Avangrid, Inc.		81,732		3,965,637
CenterPoint Energy, Inc.		130,396		3,527,212
CMS Energy Corp.		140,487		5,963,673
Exelon Corp.		207,269		7,677,244
Great Plains Energy, Inc.		101,799		2,967,441
NextEra Energy, Inc.		65,248		9,927,483
Xcel Energy, Inc.		140,324		6,073,223

			$	49,347,785
Total Common Stocks (Identified Cost, $1,420,759,564)			$	1,881,223,643

Portfolio of Investments (unaudited) – continued


Investment Companies (h) - 1.1%
Issuer	Shares/Par			Value ($)
Money Market Funds - 1.1%
MFS Institutional Money Market Portfolio, 1.52% (v) (Identified Cost, $20,101,053)		20,103,567		$	20,101,556

Collateral for Securities Loaned - 0.0%
State Street Navigator Securities Lending Government Money Market Portfolio, 1.37% (j) (Identified Cost, $614,954)		614,954		$	614,954

Securities Sold Short - (0.3)%
Telecommunications - Wireless - (0.3)%
Crown Castle International Corp., REIT (Proceeds Received, $3,678,192)		(44,300	)	$	(4,875,658	)

Other Assets, Less Liabilities - 0.2%					3,756,246
Net Assets - 100.0%				$	1,900,820,741

(a)	Non-income producing security.

(h)

An affiliated issuer may be considered one in which the fund owns 5% or more of the outstanding voting securities, or a company which is under common control. At period end, the aggregate values of the fund’s investments in affiliated issuers and in unaffiliated issuers were $20,101,556 and $1,881,838,597, respectively.

(j)	The rate quoted is the annualized seven-day yield of the fund at period end.

(l)	A portion of this security is on loan.

(s)	Security or a portion of the security was pledged to cover collateral requirements for securities sold short.

(u)	The security was valued using significant unobservable inputs and is considered level 3 under the fair value hierarchy. For further information about the fund’s level 3 holdings, please see Note 2 in the Notes to Financial Statements.

(v)	Affiliated issuer that is available only to investment companies managed by MFS. The rate quoted for the MFS Institutional Money Market Portfolio is the annualized seven-day yield of the fund at period end.

The following abbreviations are used in this report and are defined:

PLC

Public Limited Company

REIT

Real Estate Investment Trust

At February 28, 2018, the fund had cash collateral of $8,964 and other liquid securities with an aggregate value of $9,302,132 to cover any collateral or margin obligations for securities sold short and certain derivative contracts. Restricted cash and/or deposits with brokers in the Statement of Assets and Liabilities are comprised of cash collateral.

See Notes to Financial Statements

Financial Statements

STATEMENT OF ASSETS AND LIABILITIES

At 2/28/18 (unaudited)

This statement represents your fund’s balance sheet, which details the assets and liabilities comprising the total value of the fund.


Assets
Investments in unaffiliated issuers, at value, including $997,251 of securities on loan (identified cost, $1,421,374,518)			$1,881,838,597
Investments in affiliated issuers, at value (identified cost, $20,101,053)			20,101,556
Deposits with brokers for securities sold short			8,964
Receivables for
Fund shares sold			3,910,547
Interest and dividends			2,585,958
Other assets			73,695
Total assets			$1,908,519,317
Liabilities
Payables for
Securities sold short, at value (proceeds received, $3,678,192)			$4,875,658
Fund shares reacquired			1,595,621
Collateral for securities loaned, at value (c)			614,954
Payable to affiliates
Investment adviser			61,649
Shareholder servicing costs			424,450
Distribution and service fees			15,975
Payable for independent Trustees’ compensation			66,051
Accrued expenses and other liabilities			44,218
Total liabilities			$7,698,576
Net assets			$1,900,820,741
Net assets consist of
Paid-in capital			$1,343,260,162
Unrealized appreciation (depreciation)			459,267,116
Accumulated net realized gain (loss)			92,532,043
Undistributed net investment income			5,761,420
Net assets			$1,900,820,741
Shares of beneficial interest outstanding			59,840,365

(c)	Non-cash collateral is not included.

Statement of Assets and Liabilities (unaudited) – continued


	Net assets		Shares outstanding		Net asset value per share (a)
Class A		$1,057,338,216		33,584,730		$31.48
Class B		26,872,545		962,694		27.91
Class C		94,982,591		3,442,458		27.59
Class I		169,304,697		5,095,900		33.22
Class R1		3,399,640		123,304		27.57
Class R2		16,142,860		525,276		30.73
Class R3		30,942,296		985,024		31.41
Class R4		25,148,418		792,830		31.72
Class R6		476,689,478		14,328,149		33.27

(a)

Maximum offering price per share was equal to the net asset value per share for all share classes, except for Class A, for which the maximum offering price per share was $33.40 [100 / 94.25 x $31.48]. On sales of $50,000 or more, the maximum offering price of Class A shares is reduced. A contingent deferred sales charge may be imposed on redemptions of Class A, Class B, and Class C shares. Redemption price per share was equal to the net asset value per share for Classes I, R1, R2, R3, R4, and R6. Net asset value per share is calculated using actual net assets and shares outstanding rather than amounts that have been rounded for presentation purposes.

See Notes to Financial Statements

Financial Statements

STATEMENT OF OPERATIONS

Six months ended 2/28/18 (unaudited)

This statement describes how much your fund earned in investment income and accrued in expenses. It also describes any gains and/or losses generated by fund operations.


Net investment income (loss)
Income
Dividends	$14,185,253
Dividends from affiliated issuers	165,076
Interest	22,335
Income on securities loaned	14,631
Foreign taxes withheld	(24,883	)
Total investment income	$14,362,412
Expenses
Management fee	$5,233,068
Distribution and service fees	1,989,166
Shareholder servicing costs	881,217
Administrative services fee	141,056
Independent Trustees’ compensation	26,272
Custodian fee	43,304
Shareholder communications	49,656
Audit and tax fees	28,125
Legal fees	8,680
Dividend and interest expense on securities sold short	135,222
Miscellaneous	113,236
Total expenses	$8,649,002
Reduction of expenses by investment adviser and distributor	(114,095	)
Net expenses	$8,534,907
Net investment income (loss)	$5,827,505
Realized and unrealized gain (loss)
Realized gain (loss) (identified cost basis)
Unaffiliated issuers	$99,593,377
Affiliated issuers	(1,459	)
Foreign currency	1,058
Net realized gain (loss)	$99,592,976
Change in unrealized appreciation (depreciation)
Unaffiliated issuers	$73,797,081
Affiliated issuers	(1,144	)
Securities sold short	(71,766	)
Translation of assets and liabilities in foreign currencies	(280	)
Net unrealized gain (loss)	$73,723,891
Net realized and unrealized gain (loss)	$173,316,867
Change in net assets from operations	$179,144,372

See Notes to Financial Statements

Financial Statements

STATEMENTS OF CHANGES IN NET ASSETS

These statements describe the increases and/or decreases in net assets resulting from operations, any distributions, and any shareholder transactions.


Change in net assets	Six months ended 2/28/18 (unaudited)			Year ended 8/31/17
From operations
Net investment income (loss)		$5,827,505			$10,428,912
Net realized gain (loss)		99,592,976			121,534,605
Net unrealized gain (loss)		73,723,891			131,884,538
Change in net assets from operations		$179,144,372			$263,848,055
Distributions declared to shareholders
From net investment income		$(10,130,006	)		$(9,436,061	)
From net realized gain		(108,390,151	)		(45,657,548	)
Total distributions declared to shareholders		$(118,520,157	)		$(55,093,609	)
Change in net assets from fund share transactions		$144,989,157			$(66,543,205	)
Total change in net assets		$205,613,372			$142,211,241
Net assets
At beginning of period		1,695,207,369			1,552,996,128
At end of period (including undistributed net investment income of $5,761,420 and $10,063,921, respectively)		$1,900,820,741			$1,695,207,369

See Notes to Financial Statements

Financial Statements

FINANCIAL HIGHLIGHTS

The financial highlights table is intended to help you understand the fund’s financial performance for the semiannual period and the past 5 fiscal years (or life of a particular share class, if shorter). Certain information reflects financial results for a single fund share. The total returns in the table represent the rate that an investor would have earned (or lost) on an investment in the fund share class (assuming reinvestment of all distributions) held for the entire period.


	Six months ended 2/28/18			Year ended
Class A	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14			8/31/13
	(unaudited)
Net asset value, beginning of period		$30.46			$26.72			$27.19			$29.19			$23.82			$19.68
Income (loss) from investment operations
Net investment income (loss) (d)		$0.09			$0.18	(c)		$0.18			$0.15			$0.13			$0.18
Net realized and unrealized gain (loss)		3.04			4.53			2.08			0.13			5.41			4.07
Total from investment operations		$3.13			$4.71			$2.26			$0.28			$5.54			$4.25
Less distributions declared to shareholders
From net investment income		$(0.17	)		$(0.16	)		$(0.14	)		$(0.13	)		$(0.17	)		$(0.11	)
From net realized gain		(1.94	)		(0.81	)		(2.59	)		(2.15	)		—			—
Total distributions declared to shareholders		$(2.11	)		$(0.97	)		$(2.73	)		$(2.28	)		$(0.17	)		$(0.11	)
Net asset value, end of period (x)		$31.48			$30.46			$26.72			$27.19			$29.19			$23.82
Total return (%) (r)(s)(t)(x)		10.42	(n)		18.11	(c)		9.09			0.98			23.33			21.69
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.00	(a)		1.03	(c)		1.07			1.05			1.05			1.11
Expenses after expense reductions (f)		0.99	(a)		1.01	(c)		1.05			1.04			1.04			1.11
Net investment income (loss)		0.59	(a)		0.63	(c)		0.70			0.52			0.49			0.81
Portfolio turnover		22	(n)		46			68			53			48			58
Net assets at end of period (000 omitted)		$1,057,338			$992,736			$959,812			$963,167			$1,002,028			$873,139
Supplemental Ratios (%):
Ratio of expenses to average net assets after expense reductions excluding short sale expenses (f)		0.97	(a)		1.00	(c)		1.04			1.03			1.04			1.10

See Notes to Financial Statements

Financial Highlights – continued


	Six months ended 2/28/18			Year ended
Class B	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14			8/31/13
	(unaudited)
Net asset value, beginning of period		$27.17			$23.96			$24.70			$26.78			$21.88			$18.11
Income (loss) from investment operations
Net investment income (loss) (d)		$(0.02	)		$(0.03	)(c)		$(0.02	)		$(0.06	)		$(0.06	)		$0.01
Net realized and unrealized gain (loss)		2.70			4.05			1.87			0.13			4.96			3.76
Total from investment operations		$2.68			$4.02			$1.85			$0.07			$4.90			$3.77
Less distributions declared to shareholders
From net realized gain		$(1.94	)		$(0.81	)		$(2.59	)		$(2.15	)		$—			$—
Net asset value, end of period (x)		$27.91			$27.17			$23.96			$24.70			$26.78			$21.88
Total return (%) (r)(s)(t)(x)		10.02	(n)		17.21	(c)		8.24			0.25			22.39			20.82
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.75	(a)		1.78	(c)		1.82			1.80			1.80			1.86
Expenses after expense reductions (f)		1.74	(a)		1.77	(c)		1.81			1.80			1.80			1.86
Net investment income (loss)		(0.16	)(a)		(0.12	)(c)		(0.07	)		(0.23	)		(0.26	)		0.07
Portfolio turnover		22	(n)		46			68			53			48			58
Net assets at end of period (000 omitted)		$26,873			$27,139			$30,324			$34,126			$40,536			$40,495
Supplemental Ratios (%):
Ratio of expenses to average net assets after expense reductions excluding short sale expenses (f)		1.72	(a)		1.75	(c)		1.79			1.79			1.80			1.86

See Notes to Financial Statements

Financial Highlights – continued


	Six months ended 2/28/18			Year ended
Class C	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14			8/31/13
	(unaudited)
Net asset value, beginning of period		$26.88			$23.71			$24.47			$26.55			$21.72			$17.98
Income (loss) from investment operations
Net investment income (loss) (d)		$(0.02	)		$(0.03	)(c)		$(0.01	)		$(0.06	)		$(0.06	)		$0.01
Net realized and unrealized gain (loss)		2.67			4.01			1.84			0.13			4.92			3.73
Total from investment operations		$2.65			$3.98			$1.83			$0.07			$4.86			$3.74
Less distributions declared to shareholders
From net investment income		$—			$—			$—			$—			$(0.03	)		$—
From net realized gain		(1.94	)		(0.81	)		(2.59	)		(2.15	)		—			—
Total distributions declared to shareholders		$(1.94	)		$(0.81	)		$(2.59	)		$(2.15	)		$(0.03	)		$—
Net asset value, end of period (x)		$27.59			$26.88			$23.71			$24.47			$26.55			$21.72
Total return (%) (r)(s)(t)(x)		10.01	(n)		17.22	(c)		8.24			0.26			22.38			20.80
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.75	(a)		1.78	(c)		1.82			1.80			1.80			1.86
Expenses after expense reductions (f)		1.74	(a)		1.77	(c)		1.81			1.80			1.80			1.86
Net investment income (loss)		(0.16	)(a)		(0.12	)(c)		(0.05	)		(0.23	)		(0.26	)		0.06
Portfolio turnover		22	(n)		46			68			53			48			58
Net assets at end of period (000 omitted)		$94,983			$89,946			$89,160			$88,020			$89,702			$78,777
Supplemental Ratios (%):
Ratio of expenses to average net assets after expense reductions excluding short sale expenses (f)		1.72	(a)		1.75	(c)		1.79			1.79			1.80			1.86

See Notes to Financial Statements

Financial Highlights – continued


	Six months ended 2/28/18			Year ended
Class I	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14			8/31/13
	(unaudited)
Net asset value, beginning of period		$32.07			$28.10			$28.44			$30.43			$24.82			$20.49
Income (loss) from investment operations
Net investment income (loss) (d)		$0.14			$0.26	(c)		$0.29			$0.23			$0.21			$0.24
Net realized and unrealized gain (loss)		3.19			4.76			2.15			0.13			5.62			4.25
Total from investment operations		$3.33			$5.02			$2.44			$0.36			$5.83			$4.49
Less distributions declared to shareholders
From net investment income		$(0.24	)		$(0.24	)		$(0.19	)		$(0.20	)		$(0.22	)		$(0.16	)
From net realized gain		(1.94	)		(0.81	)		(2.59	)		(2.15	)		—			—
Total distributions declared to shareholders		$(2.18	)		$(1.05	)		$(2.78	)		$(2.35	)		$(0.22	)		$(0.16	)
Net asset value, end of period (x)		$33.22			$32.07			$28.10			$28.44			$30.43			$24.82
Total return (%) (r)(s)(t)(x)		10.56	(n)		18.38	(c)		9.36			1.23			23.61			22.03
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		0.75	(a)		0.78	(c)		0.81			0.80			0.80			0.86
Expenses after expense reductions (f)		0.74	(a)		0.77	(c)		0.80			0.80			0.80			0.86
Net investment income (loss)		0.85	(a)		0.88	(c)		1.07			0.77			0.73			1.05
Portfolio turnover		22	(n)		46			68			53			48			58
Net assets at end of period (000 omitted)		$169,305			$122,055			$61,739			$49,768			$45,089			$29,812
Supplemental Ratios (%):
Ratio of expenses to average net assets after expense reductions excluding short sale expenses (f)		0.73	(a)		0.75	(c)		0.79			0.79			0.80			0.86

See Notes to Financial Statements

Financial Highlights – continued


	Six months ended 2/28/18			Year ended
Class R1	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14			8/31/13
	(unaudited)
Net asset value, beginning of period		$26.86			$23.70			$24.45			$26.54			$21.69			$17.95
Income (loss) from investment operations
Net investment income (loss) (d)		$(0.02	)		$(0.03	)(c)		$(0.02	)		$(0.06	)		$(0.06	)		$0.02
Net realized and unrealized gain (loss)		2.67			4.00			1.86			0.12			4.91			3.72
Total from investment operations		$2.65			$3.97			$1.84			$0.06			$4.85			$3.74
Less distributions declared to shareholders
From net investment income		$—			$—			$—			$—			$(0.00	)(w)		$—
From net realized gain		(1.94	)		(0.81	)		(2.59	)		(2.15	)		—			—
Total distributions declared to shareholders		$(1.94	)		$(0.81	)		$(2.59	)		$(2.15	)		$(0.00	)(w)		$—
Net asset value, end of period (x)		$27.57			$26.86			$23.70			$24.45			$26.54			$21.69
Total return (%) (r)(s)(t)(x)		10.02	(n)		17.19	(c)		8.29			0.22			22.38			20.84
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.75	(a)		1.78	(c)		1.82			1.80			1.80			1.86
Expenses after expense reductions (f)		1.74	(a)		1.77	(c)		1.81			1.80			1.80			1.86
Net investment income (loss)		(0.16	)(a)		(0.13	)(c)		(0.09	)		(0.23	)		(0.26	)		0.08
Portfolio turnover		22	(n)		46			68			53			48			58
Net assets at end of period (000 omitted)		$3,400			$3,103			$2,935			$3,625			$4,132			$3,839
Supplemental Ratios (%):
Ratio of expenses to average net assets after expense reductions excluding short sale expenses (f)		1.73	(a)		1.75	(c)		1.80			1.79			1.80			1.85

See Notes to Financial Statements

Financial Highlights – continued


	Six months ended 2/28/18			Year ended
Class R2	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14			8/31/13
	(unaudited)
Net asset value, beginning of period		$29.75			$26.12			$26.62			$28.59			$23.35			$19.28
Income (loss) from investment operations
Net investment income (loss) (d)		$0.05			$0.10	(c)		$0.11			$0.07			$0.06			$0.12
Net realized and unrealized gain (loss)		2.96			4.43			2.04			0.14			5.29			4.00
Total from investment operations		$3.01			$4.53			$2.15			$0.21			$5.35			$4.12
Less distributions declared to shareholders
From net investment income		$(0.09	)		$(0.09	)		$(0.06	)		$(0.03	)		$(0.11	)		$(0.05	)
From net realized gain		(1.94	)		(0.81	)		(2.59	)		(2.15	)		—			—
Total distributions declared to shareholders		$(2.03	)		$(0.90	)		$(2.65	)		$(2.18	)		$(0.11	)		$(0.05	)
Net asset value, end of period (x)		$30.73			$29.75			$26.12			$26.62			$28.59			$23.35
Total return (%) (r)(s)(t)(x)		10.28	(n)		17.80	(c)		8.82			0.75			22.96			21.44
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.25	(a)		1.28	(c)		1.32			1.30			1.30			1.36
Expenses after expense reductions (f)		1.24	(a)		1.27	(c)		1.31			1.30			1.30			1.36
Net investment income (loss)		0.34	(a)		0.38	(c)		0.46			0.27			0.24			0.56
Portfolio turnover		22	(n)		46			68			53			48			58
Net assets at end of period (000 omitted)		$16,143			$16,508			$15,932			$16,332			$19,434			$19,625
Supplemental Ratios (%):
Ratio of expenses to average net assets after expense reductions excluding short sale expenses (f)		1.22	(a)		1.25	(c)		1.29			1.29			1.30			1.36

See Notes to Financial Statements

Financial Highlights – continued


	Six months ended 2/28/18			Year ended
Class R3	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14			8/31/13
	(unaudited)
Net asset value, beginning of period		$30.33			$26.61			$27.10			$29.10			$23.75			$19.63
Income (loss) from investment operations
Net investment income (loss) (d)		$0.09			$0.17	(c)		$0.18			$0.15			$0.13			$0.18
Net realized and unrealized gain (loss)		3.02			4.52			2.06			0.13			5.39			4.05
Total from investment operations		$3.11			$4.69			$2.24			$0.28			$5.52			$4.23
Less distributions declared to shareholders
From net investment income		$(0.09	)		$(0.16	)		$(0.14	)		$(0.13	)		$(0.17	)		$(0.11	)
From net realized gain		(1.94	)		(0.81	)		(2.59	)		(2.15	)		—			—
Total distributions declared to shareholders		$(2.03	)		$(0.97	)		$(2.73	)		$(2.28	)		$(0.17	)		$(0.11	)
Net asset value, end of period (x)		$31.41			$30.33			$26.61			$27.10			$29.10			$23.75
Total return (%) (r)(s)(t)(x)		10.42	(n)		18.10	(c)		9.06			0.99			23.32			21.68
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.00	(a)		1.02	(c)		1.07			1.05			1.05			1.11
Expenses after expense reductions (f)		0.99	(a)		1.02	(c)		1.06			1.05			1.05			1.11
Net investment income (loss)		0.59	(a)		0.62	(c)		0.71			0.52			0.49			0.81
Portfolio turnover		22	(n)		46			68			53			48			58
Net assets at end of period (000 omitted)		$30,942			$28,075			$77,217			$65,775			$68,977			$58,381
Supplemental Ratios (%):
Ratio of expenses to average net assets after expense reductions excluding short sale expenses (f)		0.98	(a)		1.00	(c)		1.04			1.04			1.05			1.10

See Notes to Financial Statements

Financial Highlights – continued


	Six months ended 2/28/18			Year ended
Class R4	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14			8/31/13
	(unaudited)
Net asset value, beginning of period		$30.71			$26.93			$27.39			$29.40			$23.99			$19.81
Income (loss) from investment operations
Net investment income (loss) (d)		$0.13			$0.25	(c)		$0.23			$0.22			$0.20			$0.23
Net realized and unrealized gain (loss)		3.06			4.57			2.11			0.12			5.44			4.11
Total from investment operations		$3.19			$4.82			$2.34			$0.34			$5.64			$4.34
Less distributions declared to shareholders
From net investment income		$(0.24	)		$(0.23	)		$(0.21	)		$(0.20	)		$(0.23	)		$(0.16	)
From net realized gain		(1.94	)		(0.81	)		(2.59	)		(2.15	)		—			—
Total distributions declared to shareholders		$(2.18	)		$(1.04	)		$(2.80	)		$(2.35	)		$(0.23	)		$(0.16	)
Net asset value, end of period (x)		$31.72			$30.71			$26.93			$27.39			$29.40			$23.99
Total return (%) (r)(s)(t)(x)		10.56	(n)		18.40	(c)		9.36			1.22			23.62			22.03
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		0.75	(a)		0.78	(c)		0.82			0.80			0.81			0.86
Expenses after expense reductions (f)		0.74	(a)		0.77	(c)		0.81			0.80			0.80			0.86
Net investment income (loss)		0.84	(a)		0.87	(c)		0.90			0.76			0.72			1.04
Portfolio turnover		22	(n)		46			68			53			48			58
Net assets at end of period (000 omitted)		$25,148			$22,494			$15,799			$21,159			$19,706			$6,165
Supplemental Ratios (%):
Ratio of expenses to average net assets after expense reductions excluding short sale expenses (f)		0.73	(a)		0.76	(c)		0.79			0.79			0.80			0.86

See Notes to Financial Statements

Financial Highlights – continued


	Six months ended 2/28/18			Year ended
Class R6	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14			8/31/13 (i)
	(unaudited)
Net asset value, beginning of period		$32.12			$28.13			$28.49			$30.47			$24.84			$21.02
Income (loss) from investment operations
Net investment income (loss) (d)		$0.15			$0.29	(c)		$0.58			$0.24			$0.23			$0.22
Net realized and unrealized gain (loss)		3.21			4.77			1.89			0.15			5.64			3.60
Total from investment operations		$3.36			$5.06			$2.47			$0.39			$5.87			$3.82
Less distributions declared to shareholders
From net investment income		$(0.27	)		$(0.26	)		$(0.24	)		$(0.22	)		$(0.24	)		$—
From net realized gain		(1.94	)		(0.81	)		(2.59	)		(2.15	)		—			—
Total distributions declared to shareholders		$(2.21	)		$(1.07	)		$(2.83	)		$(2.37	)		$(0.24	)		$—
Net asset value, end of period (x)		$33.27			$32.12			$28.13			$28.49			$30.47			$24.84
Total return (%) (r)(s)(t)(x)		10.61	(n)		18.49	(c)		9.46			1.34			23.73			18.17	(n)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		0.67	(a)		0.69	(c)		0.70			0.71			0.71			0.76	(a)
Expenses after expense reductions (f)		0.67	(a)		0.68	(c)		0.69			0.70			0.71			0.76	(a)
Net investment income (loss)		0.92	(a)		0.97	(c)		2.10			0.82			0.80			1.39	(a)
Portfolio turnover		22	(n)		46			68			53			48			58
Net assets at end of period (000 omitted)		$476,689			$393,153			$300,078			$6,198			$2,492			$119
Supplemental Ratios (%):
Ratio of expenses to average net assets after expense reductions excluding short sale expenses (f)		0.65	(a)		0.66	(c)		0.68			0.69			0.71			0.75	(a)

See Notes to Financial Statements

Financial Highlights – continued

(a)	Annualized.

(c)	Amount reflects a one-time reimbursement of expenses by the custodian (or former custodian) without which net investment income and performance would be lower and expenses would be higher.

(d)	Per share data is based on average shares outstanding.

(f)	Ratios do not reflect reductions from fees paid indirectly, if applicable.

(i)	For the period from the class inception, January 2, 2013, through the stated period end.

(n)	Not annualized.

(r)	Certain expenses have been reduced without which performance would have been lower.

(s)

From time to time the fund may receive proceeds from litigation settlements, without which performance would be lower. Excluding the effect of the proceeds received from a non-recurring litigation settlement against Household International, Inc., the total return for the year ended August 31, 2017 would have been lower by approximately 0.85%.

(t)	Total returns do not include any applicable sales charges.

(w)	Per share amount was less than $0.01.

(x)	The net asset values and total returns have been calculated on net assets which include adjustments made in accordance with U.S. generally accepted accounting principles required at period end for financial reporting purposes.

See Notes to Financial Statements

NOTES TO FINANCIAL STATEMENTS

(unaudited)

(1) Business and Organization

MFS Core Equity Fund (the fund) is a diversified series of MFS Series Trust I (the trust). The trust is organized as a Massachusetts business trust and is registered under the Investment Company Act of 1940, as amended, as an open-end management investment company.

The fund is an investment company and accordingly follows the investment company accounting and reporting guidance of the Financial Accounting Standards Board (FASB) Accounting Standards Codification Topic 946 Financial Services – Investment Companies.

(2) Significant Accounting Policies

Balance Sheet Offsetting – The fund’s accounting policy with respect to balance sheet offsetting is that, absent an event of default by the counterparty or a termination of the agreement, the International Swaps and Derivatives Association (ISDA) Master Agreement, or similar agreement, does not result in an offset of reported amounts of financial assets and financial liabilities in the Statement of Assets and Liabilities across transactions between the fund and the applicable counterparty. The fund’s right to setoff may be restricted or prohibited by the bankruptcy or insolvency laws of the particular jurisdiction to which a specific master netting agreement counterparty is subject. Balance sheet offsetting disclosures, to the extent applicable to the fund, have been included in the fund’s Significant Accounting Policies note under the captions for each of the fund’s in-scope financial instruments and transactions.

Investment Valuations – Equity securities, including restricted equity securities and equity securities held short, are generally valued at the last sale or official closing price on their primary market or exchange as provided by a third-party pricing service. Equity securities, for which there were no sales reported that day, are generally valued at the last quoted daily bid quotation on their primary market or exchange as provided by a third-party pricing service. Equity securities held short, for which there were no sales reported for that day, are generally valued at the last quoted daily ask quotation on their primary market or exchange as provided by a third-party pricing service. Short-term instruments with a maturity at issuance of 60 days or less may be valued at amortized cost, which approximates market value. Exchange-traded options are generally valued at the last sale or official closing price on their primary exchange as provided by a third-party pricing service. Exchange-traded options for which there were no sales reported that day are generally valued at the last daily bid quotation on their

Notes to Financial Statements (unaudited) – continued

primary exchange as provided by a third-party pricing service. Options not traded on an exchange are generally valued at a broker/dealer bid quotation. Foreign currency options are generally valued at valuations provided by a third-party pricing service. Open-end investment companies are generally valued at net asset value per share. Securities and other assets generally valued on the basis of information from a third-party pricing service may also be valued at a broker/dealer bid quotation. Values obtained from third-party pricing services can utilize both transaction data and market information such as yield, quality, coupon rate, maturity, type of issue, trading characteristics, and other market data. The values of foreign securities and other assets and liabilities expressed in foreign currencies are converted to U.S. dollars using the mean of bid and asked prices for rates provided by a third-party pricing service.

The Board of Trustees has delegated primary responsibility for determining or causing to be determined the value of the fund’s investments (including any fair valuation) to the adviser pursuant to valuation policies and procedures approved by the Board. If the adviser determines that reliable market quotations are not readily available, investments are valued at fair value as determined in good faith by the adviser in accordance with such procedures under the oversight of the Board of Trustees. Under the fund’s valuation policies and procedures, market quotations are not considered to be readily available for most types of debt instruments and floating rate loans and many types of derivatives. These investments are generally valued at fair value based on information from third-party pricing services. In addition, investments may be valued at fair value if the adviser determines that an investment’s value has been materially affected by events occurring after the close of the exchange or market on which the investment is principally traded (such as foreign exchange or market) and prior to the determination of the fund’s net asset value, or after the halting of trading of a specific security where trading does not resume prior to the close of the exchange or market on which the security is principally traded. Events that occur on a frequent basis after foreign markets close (such as developments in foreign markets and significant movements in the U.S. markets) and prior to the determination of the fund’s net asset value may be deemed to have a material effect on the value of securities traded in foreign markets. Accordingly, the fund’s foreign equity securities may often be valued at fair value. The adviser generally relies on third-party pricing services or other information (such as the correlation with price movements of similar securities in the same or other markets; the type, cost and investment characteristics of the security; the business and financial condition of the issuer; and trading and other market data) to assist in determining whether to fair value and at what value to fair value an investment. The value of an investment for purposes of calculating the fund’s net asset value can differ depending on the source and method used to determine value. When fair valuation is used, the value of an investment used to determine the fund’s net asset value may differ from quoted or published prices for the same investment. There can be no assurance that the fund could obtain the fair value assigned to an investment if it were to sell the investment at the same time at which the fund determines its net asset value per share.

Notes to Financial Statements (unaudited) – continued

input that is significant to the fair value measurement. The fund’s assessment of the significance of a particular input to the fair value measurement in its entirety requires judgment, and considers factors specific to the investment. Level 1 includes unadjusted quoted prices in active markets for identical assets or liabilities. Level 2 includes other significant observable market-based inputs (including quoted prices for similar securities, interest rates, prepayment speed, and credit risk). Level 3 includes unobservable inputs, which may include the adviser’s own assumptions in determining the fair value of investments. The following is a summary of the levels used as of February 28, 2018 in valuing the fund’s assets or liabilities:


Financial Instruments	Level 1			Level 2		Level 3		Total
Equity Securities		$1,881,154,619			$—		$69,024		$1,881,223,643
Mutual Funds		20,716,510			—		—		20,716,510
Total		$1,901,871,129			$—		$69,024		$1,901,940,153
Short Sales		$(4,875,658	)		$—		$—		$(4,875,658	)

For further information regarding security characteristics, see the Portfolio of Investments.

The following is a reconciliation of level 3 assets for which significant unobservable inputs were used to determine fair value. The fund’s policy is to recognize transfers between the levels as of the end of the period. The table presents the activity of level 3 securities held at the beginning and the end of the period.


	Investments in Securities
Balance as of 8/31/17		$67,353
Change in unrealized appreciation (depreciation)		1,671
Balance as of 2/28/18		$69,024

At February 28, 2018, the fund held one level 3 security.

Foreign Currency Translation – Purchases and sales of foreign investments, income, and expenses are converted into U.S. dollars based upon currency exchange rates prevailing on the respective dates of such transactions or on the reporting date for foreign denominated receivables and payables. Gains and losses attributable to foreign currency exchange rates on sales of securities are recorded for financial statement purposes as net realized gains and losses on investments. Gains and losses attributable to foreign exchange rate movements on receivables, payables, income and expenses are recorded for financial statement purposes as foreign currency transaction gains and losses. That portion of both realized and unrealized gains and losses on investments that results from fluctuations in foreign currency exchange rates is not separately disclosed.

Derivatives – The fund uses derivatives for different purposes, primarily to increase or decrease exposure to a particular market or segment of the market, or security, to increase or decrease interest rate or currency exposure, or as alternatives to direct investments. Derivatives are used for hedging or non-hedging purposes. While hedging can reduce or eliminate losses, it can also reduce or eliminate gains. When the fund uses derivatives as an investment to increase market exposure, or for hedging purposes, gains and losses from derivative instruments may be substantially greater than the derivative’s original cost.

Notes to Financial Statements (unaudited) – continued

The derivative instruments used by the fund were purchased options. Depending on the type of derivative, the fund may exit a derivative position by entering into an offsetting transaction with a counterparty or exchange, negotiating an agreement with the derivative counterparty, or novating the position to a third party. At February 28, 2018, the fund did not have any outstanding derivative instruments.

The following table presents, by major type of derivative contract, the realized gain (loss) on derivatives held by the fund for the six months ended February 28, 2018 as reported in the Statement of Operations:

Risk

Unaffiliated Issuers

(Purchased Options)

Equity

$(701,966

)

The following table presents, by major type of derivative contract, the change in unrealized appreciation (depreciation) on derivatives held by the fund for the six months ended February 28, 2018 as reported in the Statement of Operations:

Risk

Unaffiliated Issuers

(Purchased Options)

Equity

$627,125

Derivative counterparty credit risk is managed through formal evaluation of the creditworthiness of all potential counterparties. On certain, but not all, uncleared derivatives, the fund attempts to reduce its exposure to counterparty credit risk whenever possible by entering into an ISDA Master Agreement on a bilateral basis. The ISDA Master Agreement gives each party to the agreement the right to terminate all transactions traded under such agreement if there is a specified deterioration in the credit quality of the other party. Upon an event of default or a termination of the ISDA Master Agreement, the non-defaulting party has the right to close out all transactions traded under such agreement and to net amounts owed under each agreement to one net amount payable by one party to the other. This right to close out and net payments across all transactions traded under the ISDA Master Agreement could result in a reduction of the fund’s credit risk to such counterparty equal to any amounts payable by the fund under the applicable transactions, if any.

Collateral and margin requirements differ by type of derivative. For cleared derivatives (e.g., futures contracts, cleared swaps, and exchange-traded options), margin requirements are set by the clearing broker and the clearing house and collateral, in the form of cash or securities, is posted by the fund directly with the clearing broker. Collateral terms are counterparty agreement specific for uncleared derivatives (e.g., forward foreign currency exchange contracts, uncleared swap agreements, and uncleared options) and collateral, in the form of cash and securities, is held in segregated accounts with the fund’s custodian in connection with these agreements. For derivatives traded under an ISDA Master Agreement, which contains a collateral support annex, the collateral requirements are netted across all transactions traded under such counterparty-specific agreement and one amount is posted from one party to the other to collateralize such obligations. Cash that has been segregated or delivered to cover the fund’s collateral or margin obligations under derivative contracts, if any, will be reported separately in the Statement of Assets and Liabilities as restricted cash for uncleared derivatives and/or deposits with brokers for cleared derivatives.

Notes to Financial Statements (unaudited) – continued

Securities pledged as collateral or margin for the same purpose, if any, are noted in the Portfolio of Investments. The fund may be required to make payments of interest on uncovered collateral or margin obligations with the broker. Any such payments are included in “Miscellaneous” expense in the Statement of Operations.

Purchased Options – The fund purchased call options for a premium. Purchased call options entitle the holder to buy a specified number of shares or units of a particular security, currency or index at a specified price at a specified date or within a specified period of time. Purchasing call options may hedge against an anticipated increase in the dollar cost of securities or currency to be acquired or increase the fund’s exposure to an underlying instrument.

The premium paid is initially recorded as an investment in the Statement of Assets and Liabilities. That investment is subsequently marked-to-market daily with the difference between the premium paid and the market value of the purchased option being recorded as unrealized appreciation or depreciation. Premiums paid for purchased call options which have expired are treated as realized losses on investments in the Statement of Operations. Upon the exercise or closing of a purchased call option, the premium paid is added to the cost of the security or financial instrument purchased.

Whether or not the option is exercised, the fund’s maximum risk of loss from purchasing an option is the amount of premium paid. All option contracts involve credit risk if the counterparty to the option contract fails to perform. For uncleared options, this risk is mitigated in cases where there is an ISDA Master Agreement between the fund and the counterparty providing for netting as described above and, where applicable, by the posting of collateral by the counterparty to the fund to cover the fund’s exposure to the counterparty under such ISDA Master Agreement.

Short Sales – The fund entered into short sales whereby it sells a security it does not own in anticipation of a decline in the value of that security. The fund will realize a gain if the security price decreases and a loss if the security price increases between the date of the short sale and the date on which the fund replaces the borrowed security. Losses from short sales can exceed the proceeds of the security sold; and they can also exceed the potential loss from an ordinary buy and sell transaction. The amount of any premium, dividends, or interest the fund may be required to pay in connection with a short sale will be recognized as a fund expense. During the six months ended February 28, 2018, this expense amounted to $135,222. The fund segregates cash or marketable securities in an amount that, when combined with the amount of proceeds from the short sale deposited with the broker, at least equals the current market value of the security sold short.

Security Loans – Under its Securities Lending Agency Agreement with the fund, State Street Bank and Trust Company (“State Street”), as lending agent, loans the securities of the fund to certain qualified institutions (the “Borrowers”) approved by the fund. Security loans can be terminated at the discretion of either the lending agent or the fund and the related securities must be returned within the earlier of the standard trade settlement period for such securities or within three business days. The loans are collateralized by cash and/or U.S. Treasury and federal agency obligations in an amount typically at least equal to the market value of the securities loaned. On loans collateralized by cash, the cash collateral is invested in a money market fund. The

Notes to Financial Statements (unaudited) – continued

market value of the loaned securities is determined at the close of business of the fund and any additional required collateral is delivered to the fund on the next business day. State Street provides the fund with indemnification against Borrower default. In the event of Borrower default, State Street will, for the benefit of the fund, either purchase securities identical to those loaned or, when such purchase is commercially impracticable, pay the fund the market value of the loaned securities. In return, State Street assumes the fund’s rights to the related collateral. If the collateral value is less than the cost to purchase identical securities, State Street is responsible for the shortfall, but only to the extent that such shortfall is not due to a decline in collateral value resulting from collateral reinvestment for which the fund bears the risk of loss. At period end, the fund had investment securities on loan, all of which were classified as equity securities in the fund’s Portfolio of Investments, with a fair value of $997,251. The fair value of the fund’s investment securities on loan and a related liability of $614,954 for cash collateral received on securities loaned are both presented gross in the Statement of Assets and Liabilities. Additionally, these loans were collateralized by U.S. Treasury Obligations of $429,262. The collateral on securities loaned exceeded the value of securities on loan at period end. The liability for cash collateral for securities loaned is carried at fair value, which is categorized as level 2 within the fair value hierarchy. A portion of the income generated upon investment of the collateral is remitted to the Borrowers, and the remainder is allocated between the fund and the lending agent. On loans collateralized by U.S. Treasury and/or federal agency obligations, a fee is received from the Borrower, and is allocated between the fund and the lending agent. Income from securities lending is separately reported in the Statement of Operations. The dividend and interest income earned on the securities loaned is accounted for in the same manner as other dividend and interest income.

Indemnifications – Under the fund’s organizational documents, its officers and Trustees may be indemnified against certain liabilities and expenses arising out of the performance of their duties to the fund. Additionally, in the normal course of business, the fund enters into agreements with service providers that may contain indemnification clauses. The fund’s maximum exposure under these agreements is unknown as this would involve future claims that may be made against the fund that have not yet occurred.

Investment Transactions and Income – Investment transactions are recorded on the trade date. Interest income is recorded on the accrual basis. Dividends received in cash are recorded on the ex-dividend date. Certain dividends from foreign securities will be recorded when the fund is informed of the dividend if such information is obtained subsequent to the ex-dividend date. Dividend and interest payments received in additional securities are recorded on the ex-dividend or ex-interest date in an amount equal to the value of the security on such date.

The fund may receive proceeds from litigation settlements. Any proceeds received from litigation involving portfolio holdings are reflected in the Statement of Operations in realized gain/loss if the security has been disposed of by the fund or in unrealized gain/loss if the security is still held by the fund. Any other proceeds from litigation not related to portfolio holdings are reflected as other income in the Statement of Operations.

Notes to Financial Statements (unaudited) – continued

Tax Matters and Distributions – The fund intends to qualify as a regulated investment company, as defined under Subchapter M of the Internal Revenue Code, and to distribute all of its taxable income, including realized capital gains. As a result, no provision for federal income tax is required. The fund’s federal tax returns, when filed, will remain subject to examination by the Internal Revenue Service for a three year period. Management has analyzed the fund’s tax positions taken on federal and state tax returns for all open tax years and does not believe that there are any uncertain tax positions that require recognition of a tax liability. Foreign taxes, if any, have been accrued by the fund in the accompanying financial statements in accordance with the applicable foreign tax law. Foreign income taxes may be withheld by certain countries in which the fund invests. Additionally, capital gains realized by the fund on securities issued in or by certain foreign countries may be subject to capital gains tax imposed by those countries.

Distributions to shareholders are recorded on the ex-dividend date. Income and capital gain distributions are determined in accordance with income tax regulations, which may differ from U.S. generally accepted accounting principles. Certain capital accounts in the financial statements are periodically adjusted for permanent differences in order to reflect their tax character. These adjustments have no impact on net assets or net asset value per share. Temporary differences which arise from recognizing certain items of income, expense, gain or loss in different periods for financial statement and tax purposes will reverse at some time in the future. Distributions in excess of net investment income or net realized gains are temporary overdistributions for financial statement purposes resulting from differences in the recognition or classification of income or distributions for financial statement and tax purposes.

Book/tax differences primarily relate to wash sale deferrals and treating a portion of the proceeds from redemptions as a distribution for tax purposes.

The tax character of distributions made during the period will be determined at fiscal year end. The tax character of distributions declared to shareholders for the last fiscal year is as follows:


	Year ended 8/31/17
Ordinary income (including any short-term capital gains)		$9,436,061
Long-term capital gains		45,657,548
Total distributions		$55,093,609

Notes to Financial Statements (unaudited) – continued

The federal tax cost and the tax basis components of distributable earnings were as follows:


As of 2/28/18
Cost of investments	$1,441,475,571
Gross appreciation	498,367,543
Gross depreciation	(37,902,961	)
Net unrealized appreciation (depreciation)	$460,464,582

As of 8/31/17
Undistributed ordinary income	63,292,413
Undistributed long-term capital gain	51,311,988
Other temporary differences	420,805
Net unrealized appreciation (depreciation)	381,911,158

The aggregate cost above includes prior fiscal year end tax adjustments, if applicable.

Multiple Classes of Shares of Beneficial Interest – The fund offers multiple classes of shares, which differ in their respective distribution and service fees. The fund’s income, realized and unrealized gain (loss), and common expenses are allocated to shareholders based on the daily net assets of each class. Dividends are declared separately for each class. Differences in per share dividend rates are generally due to differences in separate class expenses. Class B shares will convert to Class A shares approximately eight years after purchase. Effective April 23, 2018, Class C shares will convert to Class A shares approximately ten years after purchase. The fund’s distributions declared to shareholders as reported in the Statements of Changes in Net Assets are presented by class as follows:


	From net investment income				From net realized gain
	Six months ended 2/28/18		Year ended 8/31/17		Six months ended 2/28/18		Year ended 8/31/17
Class A		$5,294,029		$5,449,582		$61,975,380		$27,694,528
Class B		—		—		1,817,848		945,376
Class C		—		—		6,378,072		2,955,565
Class I		1,130,413		754,522		8,961,582		2,519,538
Class R1		—		—		223,893		96,384
Class R2		49,766		52,754		1,036,306		473,485
Class R3		88,607		410,529		1,845,694		2,119,784
Class R4		177,188		134,267		1,420,076		482,870
Class R6		3,390,003		2,634,407		24,731,300		8,370,018
Total		$10,130,006		$9,436,061		$108,390,151		$45,657,548

(3) Transactions with Affiliates

Investment Adviser – The fund has an investment advisory agreement with MFS to provide overall investment management and related administrative services and

Notes to Financial Statements (unaudited) – continued

facilities to the fund. The management fee is computed daily and paid monthly at the following annual rates based on the fund’s average daily net assets:


Up to $500 million	0.65	%
In excess of $500 million and up to $2.5 billion	0.55	%
In excess of $2.5 billion	0.50	%

MFS has agreed in writing to reduce its management fee by a specified amount if certain MFS mutual fund assets exceed thresholds agreed to by MFS and the fund’s Board of Trustees. For the six months ended February 28, 2018, this management fee reduction amounted to $77,961, which is included in the reduction of total expenses in the Statement of Operations. The management fee incurred for the six months ended February 28, 2018 was equivalent to an annual effective rate of 0.57% of the fund’s average daily net assets.

Distributor – MFS Fund Distributors, Inc. (MFD), a wholly-owned subsidiary of MFS, as distributor, received $102,410 for the six months ended February 28, 2018, as its portion of the initial sales charge on sales of Class A shares of the fund.

The Board of Trustees has adopted a distribution plan for certain share classes pursuant to Rule 12b-1 of the Investment Company Act of 1940.

The fund’s distribution plan provides that the fund will pay MFD for services provided by MFD and financial intermediaries in connection with the distribution and servicing of certain share classes. One component of the plan is a distribution fee paid to MFD and another component of the plan is a service fee paid to MFD. MFD may subsequently pay all, or a portion, of the distribution and/or service fees to financial intermediaries.

Distribution Plan Fee Table:


	Distribution Fee Rate (d)		Service Fee Rate (d)		Total Distribution Plan (d)		Annual Effective Rate (e)		Distribution and Service Fee
Class A		—		0.25%		0.25%		0.24%		$1,291,191
Class B		0.75%		0.25%		1.00%		1.00%		135,740
Class C		0.75%		0.25%		1.00%		1.00%		466,607
Class R1		0.75%		0.25%		1.00%		1.00%		16,337
Class R2		0.25%		0.25%		0.50%		0.50%		41,694
Class R3		—		0.25%		0.25%		0.25%		37,597
Total Distribution and Service Fees										$1,989,166

(d)

In accordance with the distribution plan for certain classes, the fund pays distribution and/or service fees equal to these annual percentage rates of each class’s average daily net assets. The distribution and service fee rates disclosed by class represent the current rates in effect at the end of the reporting period. Any rate changes, if applicable, are detailed below.

(e)

The annual effective rates represent actual fees incurred under the distribution plan for the six months ended February 28, 2018 based on each class’s average daily net assets. MFD has voluntarily agreed to rebate a portion of each class’s 0.25% service fee attributable to accounts for which MFD retains the 0.25% service fee except for accounts attributable to MFS or its affiliates’ seed money. For the six months ended February 28, 2018, this rebate amounted to $33,574, $533, $1,683, and $344 for Class A, Class B, Class C, and Class R2, respectively, and is included in the reduction of total expenses in the Statement of Operations.

Notes to Financial Statements (unaudited) – continued

Certain Class A shares are subject to a contingent deferred sales charge (CDSC) in the event of a shareholder redemption within 18 months of purchase. Class C shares are subject to a CDSC in the event of a shareholder redemption within 12 months of purchase. Class B shares are subject to a CDSC in the event of a shareholder redemption within six years of purchase. All contingent deferred sales charges are paid to MFD and during the six months ended February 28, 2018, were as follows:


	Amount
Class A		$2,081
Class B		9,975
Class C		3,488

Shareholder Servicing Agent – MFS Service Center, Inc. (MFSC), a wholly-owned subsidiary of MFS, receives a fee from the fund for its services as shareholder servicing agent calculated as a percentage of the average daily net assets of the fund as determined periodically under the supervision of the fund’s Board of Trustees. For the six months ended February 28, 2018, the fee was $212,150, which equated to 0.0234% annually of the fund’s average daily net assets. MFSC also receives payment from the fund for out-of-pocket expenses, sub-accounting and other shareholder servicing costs which may be paid to affiliated and unaffiliated service providers. Class R6 shares do not incur sub-accounting fees. For the six months ended February 28, 2018, these out-of-pocket expenses, sub-accounting and other shareholder servicing costs amounted to $669,067.

Administrator – MFS provides certain financial, legal, shareholder communications, compliance, and other administrative services to the fund. Under an administrative services agreement, the fund reimburses MFS the costs incurred to provide these services. The fund is charged an annual fixed amount of $17,500 plus a fee based on average daily net assets. The administrative services fee incurred for the six months ended February 28, 2018 was equivalent to an annual effective rate of 0.0155% of the fund’s average daily net assets.

Trustees’ and Officers’ Compensation – The fund pays compensation to independent Trustees in the form of a retainer, attendance fees, and additional compensation to Board and Committee chairpersons. The fund does not pay compensation directly to Trustees or officers of the fund who are also officers of the investment adviser, all of whom receive remuneration for their services to the fund from MFS. Certain officers and Trustees of the fund are officers or directors of MFS, MFD, and MFSC.

Prior to December 31, 2001, the fund had an unfunded defined benefit plan (“DB plan”) for independent Trustees. As of December 31, 2001, the Board took action to terminate the DB plan with respect to then-current and any future independent Trustees, such that the DB plan covers only certain of those former independent Trustees who retired on or before December 31, 2001. Effective January 1, 2002, accrued benefits under the DB Plan for then-current independent Trustees who continued were credited to an unfunded retirement deferral plan (the “Retirement Deferral plan”), which was established for and exists solely with respect to these credited amounts, and is not available for other deferrals by these or other independent Trustees. Although the Retirement Deferral plan is unfunded, amounts

Notes to Financial Statements (unaudited) – continued

deferred under the plan are periodically adjusted for investment experience as if they had been invested in shares of the fund. The DB plan resulted in a pension expense of $2,621 and the Retirement Deferral plan resulted in an expense of $7,332. Both amounts are included in “Independent Trustees’ compensation” in the Statement of Operations for the six months ended February 28, 2018. The liability for deferred retirement benefits payable to certain independent Trustees under both plans amounted to $65,909 at February 28, 2018, and is included in “Payable for independent Trustees’ compensation” in the Statement of Assets and Liabilities.

Other – This fund and certain other funds managed by MFS (the funds) have entered into a service agreement (the ISO Agreement) which provides for payment of fees solely by the funds to Tarantino LLC in return for the provision of services of an Independent Senior Officer (ISO) for the funds. Frank L. Tarantino serves as the ISO and is an officer of the funds and the sole member of Tarantino LLC. The funds can terminate the ISO Agreement with Tarantino LLC at any time under the terms of the ISO Agreement. For the six months ended February 28, 2018, the fee paid by the fund under this agreement was $1,472 and is included in “Miscellaneous” expense in the Statement of Operations. MFS has agreed to bear all expenses associated with office space, other administrative support, and supplies provided to the ISO.

The fund invests in the MFS Institutional Money Market Portfolio which is managed by MFS and seeks current income consistent with preservation of capital and liquidity. This money market fund does not pay a management fee to MFS.

The fund is permitted to engage in purchase and sale transactions with funds and accounts for which MFS serves as investment adviser or sub-adviser (“cross-trades”) pursuant to a policy adopted by the Board of Trustees. This policy has been designed to ensure that cross-trades conducted by the fund comply with Rule 17a-7 under the Investment Company Act of 1940. During the six months ended February 28, 2018, the fund engaged in sale transactions pursuant to this policy, which amounted to $4,543,159. The sales transactions resulted in net realized gains (losses) of $2,128,725.

Effective January 3, 2018, the adviser has voluntarily undertaken to reimburse the fund from its own resources on a quarterly basis for the cost of investment research embedded in the cost of the fund’s securities trades. This agreement may be rescinded at any time. This reimbursement, if any, will be determined in arrears on a quarterly basis beginning with the quarter ending March 31, 2018.

(4) Portfolio Securities

For the six months ended February 28, 2018, purchases and sales of investments, other than purchased option transactions, short sales, and short-term obligations, aggregated $434,630,227 and $394,590,744, respectively.

Notes to Financial Statements (unaudited) – continued

(5) Shares of Beneficial Interest

The fund’s Declaration of Trust permits the Trustees to issue an unlimited number of full and fractional shares of beneficial interest. Transactions in fund shares were as follows:


	Six months ended 2/28/18						Year ended 8/31/17
	Shares			Amount			Shares			Amount
Shares sold
Class A		1,549,010			$48,953,372			3,357,595			$94,400,704
Class B		47,890			1,342,389			95,846			2,400,880
Class C		222,806			6,194,230			480,958			11,980,396
Class I		1,681,482			55,801,266			4,772,073			140,194,056
Class R1		6,484			179,480			23,034			567,562
Class R2		50,391			1,546,325			89,273			2,442,270
Class R3		190,907			5,996,972			191,563			5,328,845
Class R4		55,790			1,781,942			212,581			5,900,365
Class R6		2,138,458			71,305,544			3,248,472			99,927,167
		5,943,218			$193,101,520			12,471,395			$363,142,245

Shares issued to shareholders in reinvestment of distributions
Class A		2,102,570			$64,696,076			1,190,197			$31,992,477
Class B		65,187			1,780,902			38,514			928,598
Class C		229,209			6,190,943			111,646			2,662,764
Class I		297,420			9,651,266			109,935			3,106,763
Class R1		8,295			223,888			4,043			96,384
Class R2		34,320			1,031,307			18,727			492,514
Class R3		63,007			1,934,301			94,520			2,530,313
Class R4		51,558			1,597,265			22,806			617,137
Class R6		790,253			25,675,328			347,084			9,815,545
		3,641,819			$112,781,276			1,937,472			$52,242,495

Shares reacquired
Class A		(2,662,676	)		$(84,326,286	)		(7,870,881	)		$(218,624,140	)
Class B		(149,236	)		(4,204,574	)		(401,042	)		(10,025,074	)
Class C		(356,192	)		(9,892,125	)		(1,006,239	)		(25,363,246	)
Class I		(689,088	)		(23,036,289	)		(3,273,067	)		(99,289,452	)
Class R1		(6,992	)		(192,908	)		(35,410	)		(879,157	)
Class R2		(114,409	)		(3,546,487	)		(163,032	)		(4,397,972	)
Class R3		(194,645	)		(6,085,947	)		(2,261,578	)		(61,620,126	)
Class R4		(47,093	)		(1,507,101	)		(89,437	)		(2,544,126	)
Class R6		(841,881	)		(28,101,922	)		(2,022,353	)		(59,184,652	)
		(5,062,212	)		$(160,893,639	)		(17,123,039	)		$(481,927,945	)

Notes to Financial Statements (unaudited) – continued


	Six months ended 2/28/18						Year ended 8/31/17
	Shares			Amount			Shares			Amount
Net change
Class A		988,904			$29,323,162			(3,323,089	)		$(92,230,959	)
Class B		(36,159	)		(1,081,283	)		(266,682	)		(6,695,596	)
Class C		95,823			2,493,048			(413,635	)		(10,720,086	)
Class I		1,289,814			42,416,243			1,608,941			44,011,367
Class R1		7,787			210,460			(8,333	)		(215,211	)
Class R2		(29,698	)		(968,855	)		(55,032	)		(1,463,188	)
Class R3		59,269			1,845,326			(1,975,495	)		(53,760,968	)
Class R4		60,255			1,872,106			145,950			3,973,376
Class R6		2,086,830			68,878,950			1,573,203			50,558,060
		4,522,825			$144,989,157			(2,714,172	)		$(66,543,205	)

Class T shares were not publicly available for sale during the period. Please see the fund’s prospectus for details.

(6) Line of Credit

The fund and certain other funds managed by MFS participate in a $1.25 billion unsecured committed line of credit, subject to a $1 billion sublimit, provided by a syndication of banks under a credit agreement. Borrowings may be made for temporary financing needs. Interest is charged to each fund, based on its borrowings, generally at a rate equal to the higher of the Overnight Federal Reserve funds rate or daily one month LIBOR plus an agreed upon spread. A commitment fee, based on the average daily, unused portion of the committed line of credit, is allocated among the participating funds at the end of each calendar quarter. In addition, the fund and other funds managed by MFS have established unsecured uncommitted borrowing arrangements with certain banks for temporary financing needs. Interest is charged to each fund, based on its borrowings, at a rate equal to the Overnight Federal Reserve funds rate plus an agreed upon spread. For the six months ended February 28, 2018, the fund’s commitment fee and interest expense were $5,031 and $0, respectively, and are included in “Miscellaneous” expense in the Statement of Operations.

(7) Investments in Affiliated Issuers

An affiliated issuer may be considered one in which the fund owns 5% or more of the outstanding voting securities, or a company which is under common control. For the purposes of this report, the fund assumes the following to be affiliated issuers:


Affiliated Issuers				Beginning Shares/Par Amount			Acquisitions Shares/Par Amount		Dispositions Shares/Par Amount			Ending Shares/Par Amount
MFS Institutional Money Market Portfolio					26,819,115			119,568,616		(126,284,164	)		20,103,567

Affiliated Issuers	Realized Gain (Loss)			Change in Unrealized Appreciation (Depreciation)			Capital Gain Distributions		Dividend Income			Ending Value
MFS Institutional Money Market Portfolio		$(1,459	)		$(1,144	)		$—		$165,076			$20,101,556

PROXY VOTING POLICIES AND INFORMATION

MFS votes proxies on behalf of the fund pursuant to proxy voting policies and procedures that are available without charge, upon request, by calling 1-800-225-2606, by visiting mfs.com/proxyvoting, or by visiting the SEC’s Web site at http://www.sec.gov.

Information regarding how the fund voted proxies relating to portfolio securities during the most recent twelve-month period ended June 30 is available by August 31 of each year without charge by visiting mfs.com/proxyvoting, or by visiting the SEC’s Web site at http://www.sec.gov.

QUARTERLY PORTFOLIO DISCLOSURE

The fund will file a complete schedule of portfolio holdings with the Securities and Exchange Commission (the Commission) for the first and third quarters of each fiscal year on Form N-Q. A shareholder can obtain the quarterly portfolio holdings report at mfs.com. The fund’s Form N-Q is also available on the EDGAR database on the Commission’s Internet Web site at http://www.sec.gov, and may be reviewed and copied at the:

Public Reference Room

Securities and Exchange Commission

100 F Street, NE, Room 1580

Washington, D.C. 20549

Information on the operation of the Public Reference Room may be obtained by calling the Commission at 1-800-SEC-0330. Copies of the fund’s Form N-Q also may be obtained, upon payment of a duplicating fee, by electronic request at the following e-mail address: publicinfo@sec.gov or by writing the Public Reference Section at the above address.

FURTHER INFORMATION

From time to time, MFS may post important information about the fund or the MFS funds on the MFS web site (mfs.com). This information is available at https://www.mfs.com/en-us/what-we-do/announcements.html or at mfs.com/openendfunds by choosing the fund’s name.

INFORMATION ABOUT FUND CONTRACTS AND LEGAL CLAIMS

The fund has entered into contractual arrangements with an investment adviser, administrator, distributor, shareholder servicing agent, 529 program manager (if applicable), and custodian who each provide services to the fund. Unless expressly stated otherwise, shareholders are not parties to, or intended beneficiaries of these contractual arrangements, and these contractual arrangements are not intended to create any shareholder right to enforce them against the service providers or to seek any remedy under them against the service providers, either directly or on behalf of the fund.

Under the Trust’s By-Laws and Declaration of Trust, any claims asserted against or on behalf of the MFS Funds, including claims against Trustees and Officers, must be brought in state and federal courts located within the Commonwealth of Massachusetts.

PROVISION OF FINANCIAL REPORTS AND SUMMARY PROSPECTUSES

The fund produces financial reports every six months and updates its summary prospectus and prospectus annually. To avoid sending duplicate copies of materials to households, only one copy of the fund’s annual and semiannual report and summary prospectus may be mailed to shareholders having the same last name and residential address on the fund’s records. However, any shareholder may contact MFSC (please see back cover for address and telephone number) to request that copies of these reports and summary prospectuses be sent personally to that shareholder.

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CONTACT

WEB SITE

mfs.com

MFS TALK

1-800-637-8255

24 hours a day

ACCOUNT SERVICE AND LITERATURE

Shareholders

1-800-225-2606

Financial advisors

1-800-343-2829

Retirement plan services

1-800-637-1255

MAILING ADDRESS

MFS Service Center, Inc.

P.O. Box 55824

Boston, MA 02205-5824

OVERNIGHT MAIL

MFS Service Center, Inc.

c/o DST Asset Manager Solutions, Inc.

30 Dan Road

Canton, MA 02021-2809

Semiannual Report

February 28, 2018

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MFS® Low Volatility Global Equity Fund

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LVO-SEM

MFS® Low Volatility Global Equity Fund

CONTENTS


Letter from the Executive Chairman			1
Portfolio composition			2
Expense table			4
Portfolio of investments			6
Statement of assets and liabilities			11
Statement of operations			13
Statements of changes in net assets			14
Financial highlights			15
Notes to financial statements			21
Proxy voting policies and information			32
Quarterly portfolio disclosure			32
Further information			32
Information about fund contracts and legal claims			33
Provision of financial reports and summary prospectuses			33
Contact information back cover

The report is prepared for the general information of shareholders.

It is authorized for distribution to prospective investors only when preceded or accompanied by a current prospectus.

NOT FDIC INSURED • MAY LOSE VALUE • NO BANK GUARANTEE

LOGO

LETTER FROM THE EXECUTIVE CHAIRMAN

Dear Shareholders:

Rising bond yields have led to a measurable uptick in market volatility — a departure from the low-volatility environment that prevailed for much of 2017. In spite of this,

U.S. protectionism is also a growing concern, as investors fear that trade friction could disrupt the synchronized uptick in global growth.

Respectfully,

LOGO

Robert J. Manning

Executive Chairman

MFS Investment Management

April 13, 2018

The opinions expressed in this letter are subject to change and may not be relied upon for investment advice. No forecasts can be guaranteed.

PORTFOLIO COMPOSITION

Portfolio structure

LOGO


Top ten holdings
Taiwan Semiconductor Manufacturing Co. Ltd., ADR			3.2%
Terumo Corp.			2.9%
Johnson & Johnson			2.7%
ABC-MART, Inc.			2.2%
Ross Stores, Inc.			2.2%
Roche Holding AG			2.1%
Lockheed Martin Corp.			2.0%
Fisher & Paykel Healthcare Corp. Ltd.			2.0%
Pfizer, Inc.			2.0%
NICE Systems Ltd., ADR			1.9%

Equity sectors
Financial Services			16.4%
Utilities & Communications			16.2%
Health Care			15.3%
Consumer Staples			12.9%
Technology			12.0%
Retailing			8.5%
Basic Materials			4.5%
Industrial Goods & Services			3.7%
Autos & Housing			2.9%
Energy			2.8%
Leisure			2.2%
Special Products & Services			1.0%
Transportation			0.8%


Issuer country weightings (x)
United States			43.9%
Japan			12.7%
Canada			9.3%
Switzerland			6.6%
Hong Kong			4.8%
United Kingdom			4.0%
Taiwan			3.2%
Germany			2.7%
New Zealand			2.0%
Other Countries			10.8%

Currency exposure weightings (y)
United States Dollar			53.5%
Japanese Yen			12.7%
Swiss Franc			6.6%
Euro			4.1%
British Pound Sterling			4.0%
Hong Kong Dollar			3.8%
Taiwan Dollar			3.2%
New Zealand Dollar			2.0%
Israeli Shekel			1.9%
Other Currencies			8.2%

Portfolio Composition – continued

(x)	Represents the portfolio’s exposure to issuer countries as a percentage of a portfolio’s net assets. For purposes of this presentation, United States includes Cash & Cash Equivalents.

(y)	Represents the portfolio’s exposure to a particular currency as a percentage of a portfolio’s net assets. For purposes of this presentation, United States Dollar includes Cash & Cash Equivalents.

Percentages are based on net assets as of February 28, 2018.

The portfolio is actively managed and current holdings may be different.

EXPENSE TABLE

Fund expenses borne by the shareholders during the period, September 1, 2017 through February 28, 2018

The example is based on an investment of $1,000 invested at the beginning of the period and held for the entire period September 1, 2017 through February 28, 2018.

Actual Expenses

Hypothetical Example for Comparison Purposes

Expense Table – continued


Share Class		Annualized Expense Ratio		Beginning Account Value 9/01/17		Ending Account Value 2/28/18		Expenses Paid During Period (p) 9/01/17-2/28/18
A	Actual		0.95%		$1,000.00		$1,035.81		$4.80
A	Hypothetical (h)		0.95%		$1,000.00		$1,020.08		$4.76
B	Actual		1.74%		$1,000.00		$1,031.05		$8.76
B	Hypothetical (h)		1.74%		$1,000.00		$1,016.17		$8.70
C	Actual		1.74%		$1,000.00		$1,030.77		$8.76
C	Hypothetical (h)		1.74%		$1,000.00		$1,016.17		$8.70
I	Actual		0.74%		$1,000.00		$1,036.13		$3.74
I	Hypothetical (h)		0.74%		$1,000.00		$1,021.12		$3.71
R1	Actual		1.74%		$1,000.00		$1,031.61		$8.76
R1	Hypothetical (h)		1.74%		$1,000.00		$1,016.17		$8.70
R2	Actual		1.24%		$1,000.00		$1,034.22		$6.25
R2	Hypothetical (h)		1.24%		$1,000.00		$1,018.65		$6.21
R3	Actual		0.99%		$1,000.00		$1,035.22		$5.00
R3	Hypothetical (h)		0.99%		$1,000.00		$1,019.89		$4.96
R4	Actual		0.74%		$1,000.00		$1,036.12		$3.74
R4	Hypothetical (h)		0.74%		$1,000.00		$1,021.12		$3.71
R6	Actual	��	0.67%		$1,000.00		$1,036.47		$3.38
R6	Hypothetical (h)		0.67%		$1,000.00		$1,021.47		$3.36

(h)	5% class return per year before expenses.

(p)

Notes to Expense Table

Each class with a Rule 12b-1 service fee is subject to a rebate of a portion of such fee. Such rebates are included in the expense ratios above and are outside of the expense limitation arrangement. For Class A shares, this rebate reduced the expense ratio above by 0.04%. See Note 3 in the Notes to Financial Statements for additional information.

PORTFOLIO OF INVESTMENTS

2/28/18 (unaudited)

The Portfolio of Investments is a complete list of all securities owned by your fund. It is categorized by broad-based asset classes.


Common Stocks - 99.2%
Issuer	Shares/Par		Value ($)
Aerospace - 2.0%
Lockheed Martin Corp.		10,653	$	3,754,543

Alcoholic Beverages - 0.5%
Remy Cointreau S.A.		6,180	$	841,256

Apparel Manufacturers - 0.5%
Gildan Activewear, Inc.		28,670	$	829,996

Automotive - 2.3%
Kia Motors Corp.		70,742	$	2,237,090
USS Co. Ltd.		92,400		1,902,575

			$	4,139,665
Business Services - 1.0%
Forrester Research, Inc.		46,313	$	1,875,676

Cable TV - 0.4%
Comcast Corp., “A”		18,098	$	655,329

Chemicals - 0.8%
Monsanto Co.		12,235	$	1,509,432

Computer Software - 1.9%
Adobe Systems, Inc. (a)		16,477	$	3,445,835

Computer Software - Systems - 1.9%
NICE Systems Ltd., ADR (a)		35,686	$	3,446,911

Construction - 0.6%
Owens Corning		14,193	$	1,153,891

Consumer Products - 2.3%
Kimberly-Clark Corp.		14,451	$	1,602,905
L’Oréal		3,390		730,632
Procter & Gamble Co.		23,232		1,824,177

			$	4,157,714

Portfolio of Investments (unaudited) – continued


Issuer	Shares/Par		Value ($)
Common Stocks - continued
Electronics - 4.8%
Kyocera Corp.		49,300	$	2,902,485
Taiwan Semiconductor Manufacturing Co. Ltd., ADR		137,465		5,959,108

			$	8,861,593
Energy - Independent - 0.8%
Occidental Petroleum Corp.		21,202	$	1,390,851

Energy - Integrated - 2.1%
Exxon Mobil Corp.		28,380	$	2,149,501
Royal Dutch Shell PLC, “B”		53,056		1,682,606

			$	3,832,107
Food & Beverages - 8.6%
Ezaki Glico Co. Ltd.		17,800	$	868,408
General Mills, Inc.		43,022		2,174,762
Marine Harvest (l)		82,560		1,600,974
Mondelez International, Inc.		25,226		1,107,421
Nestle S.A.		37,381		2,975,533
PepsiCo, Inc.		30,457		3,342,047
Sligro Food Group N.V.		21,072		1,093,738
Toyo Suisan Kaisha Ltd.		55,500		2,168,707
Tyson Foods, Inc., “A”		7,330		545,205

			$	15,876,795
Food & Drug Stores - 2.8%
Dairy Farm International Holdings Ltd.		208,900	$	1,762,165
Lawson, Inc.		35,200		2,296,395
METRO, Inc., “A”		33,421		1,054,304

			$	5,112,864
Insurance - 4.8%
Beazley PLC		210,746	$	1,505,972
Everest Re Group Ltd.		3,235		777,176
Intact Financial Corp.		24,608		1,903,323
Swiss Life Holding AG		3,981		1,443,845
Travelers Cos., Inc.		6,052		841,228
XL Group Ltd.		21,852		924,558
Zurich Insurance Group AG		4,216		1,390,913

			$	8,787,015
Internet - 2.2%
Alphabet, Inc., “A” (a)		1,314	$	1,450,551
Facebook, Inc., “A” (a)		14,535		2,591,881

			$	4,042,432

Portfolio of Investments (unaudited) – continued


Issuer	Shares/Par		Value ($)
Common Stocks - continued
Machinery & Tools - 0.8%
Schindler Holding AG		3,451	$	808,429
Schindler Holding AG		2,774		628,192

			$	1,436,621
Major Banks - 2.4%
Bank of Nova Scotia		16,593	$	1,028,102
HSBC Holdings PLC, ADR (l)		32,635		1,619,675
Royal Bank of Canada		22,714		1,791,908

			$	4,439,685
Medical & Health Technology & Services - 0.8%
Express Scripts Holding Co. (a)		18,965	$	1,430,909

Medical Equipment - 5.9%
Abbott Laboratories		19,003	$	1,146,451
Fisher & Paykel Healthcare Corp. Ltd.		370,996		3,670,915
Integra LifeSciences Holdings Corp. (a)		12,421		654,959
Terumo Corp.		99,500		5,380,899

			$	10,853,224
Natural Gas - Distribution - 0.5%
Osaka Gas Co. Ltd.		48,900	$	965,577

Natural Gas - Pipeline - 0.9%
Enbridge, Inc.		51,683	$	1,644,553

Network & Telecom - 1.2%
VTech Holdings Ltd.		163,700	$	2,250,432

Other Banks & Diversified Financials - 3.3%
Banco de Oro Unibank, Inc.		293,330	$	877,512
Credicorp Ltd.		8,334		1,803,894
Discover Financial Services		13,543		1,067,595
Public Bank Berhad		190,000		1,112,144
Sydbank A.S.		30,022		1,173,105

			$	6,034,250
Pharmaceuticals - 8.6%
Johnson & Johnson		38,179	$	4,958,689
Merck & Co., Inc.		40,936		2,219,550
Novartis AG		12,974		1,085,501
Pfizer, Inc.		100,626		3,653,730
Roche Holding AG		16,556		3,838,817

			$	15,756,287

Portfolio of Investments (unaudited) – continued


Issuer	Shares/Par		Value ($)
Common Stocks - continued
Pollution Control - 0.9%
Waste Connections, Inc.		23,790	$	1,683,856

Precious Metals & Minerals - 1.1%
Franco-Nevada Corp.		30,160	$	2,113,456

Railroad & Shipping - 0.8%
Canadian National Railway Co.		17,875	$	1,382,989

Real Estate - 5.9%
AvalonBay Communities, Inc., REIT		14,208	$	2,216,732
Grand City Properties S.A.		135,339		3,033,137
Public Storage, Inc., REIT		5,909		1,148,946
Starwood Property Trust, Inc., REIT		34,650		701,662
Store Capital Corp., REIT		67,338		1,605,338
Sun Communities, Inc., REIT		24,391		2,135,676

			$	10,841,491
Restaurants - 1.8%
McDonald’s Corp.		21,266	$	3,354,499

Specialty Chemicals - 2.5%
PTT Global Chemical PLC		899,400	$	2,843,754
Symrise AG		22,523		1,831,103

			$	4,674,857
Specialty Stores - 5.3%
ABC-MART, Inc.		65,000	$	4,119,538
Home Depot, Inc.		8,444		1,539,088
Ross Stores, Inc.		51,946		4,056,463

			$	9,715,089
Telecommunications - Wireless - 3.3%
KDDI Corp.		109,300	$	2,684,944
SBA Communications Corp., REIT (a)		5,580		877,567
Vodafone Group PLC		900,360		2,520,834

			$	6,083,345
Telephone Services - 4.9%
BCE, Inc.		15,994	$	697,818
HKT Trust and HKT Ltd.		1,617,000		2,061,460
TDC A.S.		189,328		1,543,262
TELUS Corp.		82,467		2,977,059
Verizon Communications, Inc.		37,776		1,803,426

			$	9,083,025

Portfolio of Investments (unaudited) – continued


Issuer	Shares/Par		Value ($)
Common Stocks - continued
Tobacco - 1.5%
Altria Group, Inc.		34,906	$	2,197,332
British American Tobacco		84,500		612,663

			$	2,809,995
Utilities - Electric Power - 6.5%
Alliant Energy Corp.		55,361	$	2,139,703
American Electric Power Co., Inc.		24,010		1,574,576
Avangrid, Inc.		27,075		1,313,679
CLP Holdings Ltd.		268,500		2,705,938
Duke Energy Corp.		9,122		687,251
WEC Energy Group, Inc.		27,313		1,636,595
Xcel Energy, Inc.		45,722		1,978,848

			$	12,036,590
Total Common Stocks (Identified Cost, $161,515,768)			$	182,304,635

Investment Companies (h) - 0.8%
Money Market Funds - 0.8%
MFS Institutional Money Market Portfolio, 1.52% (v) (Identified Cost, $1,507,483)		1,507,700	$	1,507,549

Collateral for Securities Loaned - 1.6%
State Street Navigator Securities Lending Government Money Market Portfolio, 1.37% (j) (Identified Cost, $2,957,531)		2,957,531	$	2,957,531

Other Assets, Less Liabilities - (1.6)%				(2,892,114	)
Net Assets - 100.0%			$	183,877,601

(a)	Non-income producing security.

(h)

(j)	The rate quoted is the annualized seven-day yield of the fund at period end.

(l)	A portion of this security is on loan.

(v)	Affiliated issuer that is available only to investment companies managed by MFS. The rate quoted for the MFS Institutional Money Market Portfolio is the annualized seven-day yield of the fund at period end.

The following abbreviations are used in this report and are defined:

ADR

American Depositary Receipt

PLC

Public Limited Company

REIT

Real Estate Investment Trust

See Notes to Financial Statements

Financial Statements

STATEMENT OF ASSETS AND LIABILITIES

At 2/28/18 (unaudited)

This statement represents your fund’s balance sheet, which details the assets and liabilities comprising the total value of the fund.


Assets
Investments in unaffiliated issuers, at value, including $2,838,106 of securities on loan (identified cost, $164,473,299)	$185,262,166
Investments in affiliated issuers, at value (identified cost, $1,507,483)	1,507,549
Receivables for
Investments sold	1,633,750
Fund shares sold	434,477
Interest and dividends	474,449
Receivable from investment adviser	1,135
Receivable from distributor	340
Other assets	1,085
Total assets	$189,314,951
Liabilities
Payables for
Investments purchased	$2,232,045
Fund shares reacquired	90,693
Collateral for securities loaned, at value	2,957,531
Payable to affiliates
Shareholder servicing costs	18,587
Payable for independent Trustees’ compensation	12
Deferred country tax expense payable	137,569
Accrued expenses and other liabilities	913
Total liabilities	$5,437,350
Net assets	$183,877,601
Net assets consist of
Paid-in capital	$164,832,922
Unrealized appreciation (depreciation) (net of $137,569 deferred country tax)	20,654,321
Accumulated net realized gain (loss)	(1,424,790	)
Accumulated distributions in excess of net investment income	(184,852	)
Net assets	$183,877,601
Shares of beneficial interest outstanding	14,022,494

Statement of Assets and Liabilities (unaudited) – continued


	Net assets		Shares outstanding		Net asset value per share (a)
Class A		$9,726,249		741,515		$13.12
Class B		375,118		28,795		13.03
Class C		2,120,879		162,954		13.02
Class I		104,072,158		7,932,978		13.12
Class R1		70,294		5,372		13.09
Class R2		62,987		4,801		13.12
Class R3		63,366		4,826		13.13
Class R4		63,771		4,861		13.12
Class R6		67,322,779		5,136,392		13.11

(a)

Maximum offering price per share was equal to the net asset value per share for all share classes, except for Class A, for which the maximum offering price per share was $13.92 [100 / 94.25 x $13.12]. On sales of $50,000 or more, the maximum offering price of Class A shares is reduced. A contingent deferred sales charge may be imposed on redemptions of Class A, Class B, and Class C shares. Redemption price per share was equal to the net asset value per share for Classes I, R1, R2, R3, R4, and R6. Net asset value per share is calculated using actual net assets and shares outstanding rather than amounts that have been rounded for presentation purposes.

See Notes to Financial Statements

Financial Statements

STATEMENT OF OPERATIONS

Six months ended 2/28/18 (unaudited)

This statement describes how much your fund earned in investment income and accrued in expenses. It also describes any gains and/or losses generated by fund operations.


Net investment income (loss)
Income
Dividends	$1,869,374
Dividends from affiliated issuers	7,261
Income on securities loaned	3,008
Interest	5
Foreign taxes withheld	(80,804	)
Total investment income	$1,798,844
Expenses
Management fee	$500,292
Distribution and service fees	24,503
Shareholder servicing costs	43,303
Administrative services fee	18,621
Independent Trustees’ compensation	1,629
Custodian fee	26,237
Shareholder communications	9,319
Audit and tax fees	26,932
Legal fees	842
Registration fees	66,188
Miscellaneous	10,478
Total expenses	$728,344
Reduction of expenses by investment adviser and distributor	(54,028	)
Net expenses	$674,316
Net investment income (loss)	$1,124,528
Realized and unrealized gain (loss)
Realized gain (loss) (identified cost basis)
Unaffiliated issuers (net of $4,706 country tax)	$722,567
Affiliated issuers	(79	)
Foreign currency	4,575
Net realized gain (loss)	$727,063
Change in unrealized appreciation (depreciation)
Unaffiliated issuers (net of $94,961 increase in deferred country tax)	$4,531,436
Affiliated issuers	59
Translation of assets and liabilities in foreign currencies	(4	)
Net unrealized gain (loss)	$4,531,491
Net realized and unrealized gain (loss)	$5,258,554
Change in net assets from operations	$6,383,082

See Notes to Financial Statements

Financial Statements

STATEMENTS OF CHANGES IN NET ASSETS

These statements describe the increases and/or decreases in net assets resulting from operations, any distributions, and any shareholder transactions.


	Six months ended			Year ended
	2/28/18			8/31/17
Change in net assets	(unaudited)
From operations
Net investment income (loss)		$1,124,528			$1,908,001
Net realized gain (loss)		727,063			(342,502	)
Net unrealized gain (loss)		4,531,491			10,193,013
Change in net assets from operations		$6,383,082			$11,758,512
Distributions declared to shareholders
From net investment income		$(2,245,957	)		$(1,436,284	)
Change in net assets from fund share transactions		$1,391,148			$101,951,299
Total change in net assets		$5,528,273			$112,273,527
Net assets
At beginning of period		178,349,328			66,075,801
At end of period (including accumulated distributions in excess of net investment income of $184,852 and undistributed net investment income of $936,577)		$183,877,601			$178,349,328

See Notes to Financial Statements

Financial Statements

FINANCIAL HIGHLIGHTS


	Six months ended 2/28/18			Year ended
Class A	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14 (c)
	(unaudited)
Net asset value, beginning of period		$12.82			$11.87			$10.75			$10.92			$10.00
Income (loss) from investment operations
Net investment income (loss) (d)		$0.07			$0.19			$0.18			$0.19			$0.15
Net realized and unrealized gain (loss)		0.38			0.91			1.11			(0.22	)		0.86
Total from investment operations		$0.45			$1.10			$1.29			$(0.03	)		$1.01
Less distributions declared to shareholders
From net investment income		$(0.15	)		$(0.15	)		$(0.17	)		$(0.12	)		$(0.09	)
From net realized gain		—			—			—			(0.02	)		—
Total distributions declared to shareholders		$(0.15	)		$(0.15	)		$(0.17	)		$(0.14	)		$(0.09	)
Net asset value, end of period (x)		$13.12			$12.82			$11.87			$10.75			$10.92
Total return (%) (r)(s)(t)(x)		3.50	(n)		9.36			12.12			(0.36	)		10.13	(n)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.05	(a)		1.23			1.51			1.88			5.81	(a)
Expenses after expense reductions (f)		0.95	(a)		1.17			1.19			1.23			1.22	(a)
Net investment income (loss)		1.01	(a)(l)		1.55			1.56			1.65			1.86	(a)
Portfolio turnover		17	(n)		24			28			61			28	(n)
Net assets at end of period (000 omitted)		$9,726			$9,215			$7,473			$3,981			$800

See Notes to Financial Statements

Financial Highlights – continued


	Six months ended 2/28/18			Year ended
Class B	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14 (c)
	(unaudited)
Net asset value, beginning of period		$12.73			$11.79			$10.70			$10.91			$10.00
Income (loss) from investment operations
Net investment income (loss) (d)		$0.01			$0.09			$0.07			$0.08			$0.06
Net realized and unrealized gain (loss)		0.38			0.91			1.12			(0.20	)		0.89
Total from investment operations		$0.39			$1.00			$1.19			$(0.12	)		$0.95
Less distributions declared to shareholders
From net investment income		$(0.09	)		$(0.06	)		$(0.10	)		$(0.07	)		$(0.04	)
From net realized gain		—			—			—			(0.02	)		—
Total distributions declared to shareholders		$(0.09	)		$(0.06	)		$(0.10	)		$(0.09	)		$(0.04	)
Net asset value, end of period (x)		$13.03			$12.73			$11.79			$10.70			$10.91
Total return (%) (r)(s)(t)(x)		3.10	(n)		8.48			11.16			(1.16	)		9.50	(n)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.80	(a)		1.98			2.33			2.68			6.87	(a)
Expenses after expense reductions (f)		1.74	(a)		1.96			1.98			2.01			2.07	(a)
Net investment income (loss)		0.23	(a)(l)		0.73			0.65			0.74			0.80	(a)
Portfolio turnover		17	(n)		24			28			61			28	(n)
Net assets at end of period (000 omitted)		$375			$350			$341			$446			$116

	Six months ended 2/28/18			Year ended
Class C	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14 (c)
	(unaudited)
Net asset value, beginning of period		$12.71			$11.78			$10.69			$10.91			$10.00
Income (loss) from investment operations
Net investment income (loss) (d)		$0.02			$0.09			$0.08			$0.10			$0.06
Net realized and unrealized gain (loss)		0.38			0.91			1.11			(0.23	)		0.89
Total from investment operations		$0.40			$1.00			$1.19			$(0.13	)		$0.95
Less distributions declared to shareholders
From net investment income		$(0.09	)		$(0.07	)		$(0.10	)		$(0.07	)		$(0.04	)
From net realized gain		—			—			—			(0.02	)		—
Total distributions declared to shareholders		$(0.09	)		$(0.07	)		$(0.10	)		$(0.09	)		$(0.04	)
Net asset value, end of period (x)		$13.02			$12.71			$11.78			$10.69			$10.91
Total return (%) (r)(s)(t)(x)		3.16	(n)		8.49			11.22			(1.23	)		9.50	(n)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.80	(a)		1.98			2.23			2.66			6.85	(a)
Expenses after expense reductions (f)		1.74	(a)		1.96			1.99			2.00			2.07	(a)
Net investment income (loss)		0.25	(a)(l)		0.76			0.74			0.89			0.82	(a)
Portfolio turnover		17	(n)		24			28			61			28	(n)
Net assets at end of period (000 omitted)		$2,121			$1,924			$1,554			$453			$130

See Notes to Financial Statements

Financial Highlights – continued


	Six months ended 2/28/18			Year ended
Class I	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14 (c)
	(unaudited)
Net asset value, beginning of period		$12.82			$11.87			$10.76			$10.93			$10.00
Income (loss) from investment operations
Net investment income (loss) (d)		$0.08			$0.23			$0.21			$0.24			$0.14
Net realized and unrealized gain (loss)		0.38			0.90			1.10			(0.25	)		0.89
Total from investment operations		$0.46			$1.13			$1.31			$(0.01	)		$1.03
Less distributions declared to shareholders
From net investment income		$(0.16	)		$(0.18	)		$(0.20	)		$(0.14	)		$(0.10	)
From net realized gain		—			—			—			(0.02	)		—
Total distributions declared to shareholders		$(0.16	)		$(0.18	)		$(0.20	)		$(0.16	)		$(0.10	)
Net asset value, end of period (x)		$13.12			$12.82			$11.87			$10.76			$10.93
Total return (%) (r)(s)(t)(x)		3.61	(n)		9.59			12.34			(0.18	)		10.29	(n)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		0.80	(a)		0.94			1.17			1.63			5.85	(a)
Expenses after expense reductions (f)		0.74	(a)		0.90			0.98			1.00			1.07	(a)
Net investment income (loss)		1.23	(a)(l)		1.87			1.86			2.10			1.81	(a)
Portfolio turnover		17	(n)		24			28			61			28	(n)
Net assets at end of period (000 omitted)		$104,072			$97,952			$10,669			$2,685			$138

	Six months ended 2/28/18			Year ended
Class R1	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14 (c)
	(unaudited)
Net asset value, beginning of period		$12.78			$11.84			$10.70			$10.91			$10.00
Income (loss) from investment operations
Net investment income (loss) (d)		$0.01			$0.09			$0.08			$0.07			$0.06
Net realized and unrealized gain (loss)		0.39			0.91			1.12			(0.19	)		0.89
Total from investment operations		$0.40			$1.00			$1.20			$(0.12	)		$0.95
Less distributions declared to shareholders
From net investment income		$(0.09	)		$(0.06	)		$(0.06	)		$(0.07	)		$(0.04	)
From net realized gain		—			—			—			(0.02	)		—
Total distributions declared to shareholders		$(0.09	)		$(0.06	)		$(0.06	)		$(0.09	)		$(0.04	)
Net asset value, end of period (x)		$13.09			$12.78			$11.84			$10.70			$10.91
Total return (%) (r)(s)(t)(x)		3.16	(n)		8.47			11.24			(1.22	)		9.50	(n)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.80	(a)		1.98			2.31			2.69			6.89	(a)
Expenses after expense reductions (f)		1.74	(a)		1.96			1.99			2.01			2.07	(a)
Net investment income (loss)		0.23	(a)(l)		0.75			0.69			0.66			0.79	(a)
Portfolio turnover		17	(n)		24			28			61			28	(n)
Net assets at end of period (000 omitted)		$70			$68			$56			$108			$109

See Notes to Financial Statements

Financial Highlights – continued


	Six months ended 2/28/18			Year ended
Class R2	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14 (c)
	(unaudited)
Net asset value, beginning of period		$12.81			$11.87			$10.74			$10.92			$10.00
Income (loss) from investment operations
Net investment income (loss) (d)		$0.05			$0.15			$0.13			$0.13			$0.10
Net realized and unrealized gain (loss)		0.39			0.90			1.13			(0.20	)		0.89
Total from investment operations		$0.44			$1.05			$1.26			$(0.07	)		$0.99
Less distributions declared to shareholders
From net investment income		$(0.13	)		$(0.11	)		$(0.13	)		$(0.09	)		$(0.07	)
From net realized gain		—			—			—			(0.02	)		—
Total distributions declared to shareholders		$(0.13	)		$(0.11	)		$(0.13	)		$(0.11	)		$(0.07	)
Net asset value, end of period (x)		$13.12			$12.81			$11.87			$10.74			$10.92
Total return (%) (r)(s)(t)(x)		3.42	(n)		8.94			11.83			(0.71	)		9.89	(n)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.30	(a)		1.49			1.79			2.19			6.39	(a)
Expenses after expense reductions (f)		1.24	(a)		1.47			1.49			1.51			1.57	(a)
Net investment income (loss)		0.73	(a)(l)		1.24			1.20			1.16			1.29	(a)
Portfolio turnover		17	(n)		24			28			61			28	(n)
Net assets at end of period (000 omitted)		$63			$61			$72			$112			$110

	Six months ended 2/28/18			Year ended
Class R3	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14 (c)
	(unaudited)
Net asset value, beginning of period		$12.82			$11.88			$10.76			$10.92			$10.00
Income (loss) from investment operations
Net investment income (loss) (d)		$0.07			$0.19			$0.16			$0.16			$0.12
Net realized and unrealized gain (loss)		0.38			0.90			1.12			(0.19	)		0.88
Total from investment operations		$0.45			$1.09			$1.28			$(0.03	)		$1.00
Less distributions declared to shareholders
From net investment income		$(0.14	)		$(0.15	)		$(0.16	)		$(0.11	)		$(0.08	)
From net realized gain		—			—			—			(0.02	)		—
Total distributions declared to shareholders		$(0.14	)		$(0.15	)		$(0.16	)		$(0.13	)		$(0.08	)
Net asset value, end of period (x)		$13.13			$12.82			$11.88			$10.76			$10.92
Total return (%) (r)(s)(t)(x)		3.52	(n)		9.24			12.05			(0.34	)		10.04	(n)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.04	(a)		1.21			1.56			1.94			6.14	(a)
Expenses after expense reductions (f)		0.99	(a)		1.18			1.24			1.26			1.32	(a)
Net investment income (loss)		1.06	(a)(l)		1.55			1.44			1.41			1.54	(a)
Portfolio turnover		17	(n)		24			28			61			28	(n)
Net assets at end of period (000 omitted)		$63			$151			$56			$110			$110

See Notes to Financial Statements

Financial Highlights – continued


	Six months ended 2/28/18			Year ended
Class R4	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14 (c)
	(unaudited)
Net asset value, beginning of period		$12.82			$11.87			$10.76			$10.93			$10.00
Income (loss) from investment operations
Net investment income (loss) (d)		$0.08			$0.21			$0.19			$0.19			$0.14
Net realized and unrealized gain (loss)		0.38			0.92			1.12			(0.20	)		0.89
Total from investment operations		$0.46			$1.13			$1.31			$(0.01	)		$1.03
Less distributions declared to shareholders
From net investment income		$(0.16	)		$(0.18	)		$(0.20	)		$(0.14	)		$(0.10	)
From net realized gain		—			—			—			(0.02	)		—
Total distributions declared to shareholders		$(0.16	)		$(0.18	)		$(0.20	)		$(0.16	)		$(0.10	)
Net asset value, end of period (x)		$13.12			$12.82			$11.87			$10.76			$10.93
Total return (%) (r)(s)(t)(x)		3.61	(n)		9.58			12.32			(0.18	)		10.29	(n)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		0.80	(a)		0.98			1.31			1.69			5.89	(a)
Expenses after expense reductions (f)		0.74	(a)		0.96			0.99			1.02			1.07	(a)
Net investment income (loss)		1.24	(a)(l)		1.74			1.69			1.66			1.79	(a)
Portfolio turnover		17	(n)		24			28			61			28	(n)
Net assets at end of period (000 omitted)		$64			$62			$56			$110			$110

	Six months ended 2/28/18			Year ended
Class R6	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14 (c)
	(unaudited)
Net asset value, beginning of period		$12.81			$11.86			$10.76			$10.92			$10.00
Income (loss) from investment operations
Net investment income (loss) (d)		$0.09			$0.21			$0.20			$0.20			$0.14
Net realized and unrealized gain (loss)		0.38			0.92			1.11			(0.20	)		0.88
Total from investment operations		$0.47			$1.13			$1.31			$0.00			$1.02
Less distributions declared to shareholders
From net investment income		$(0.17	)		$(0.18	)		$(0.21	)		$(0.14	)		$(0.10	)
From net realized gain		—			—			—			(0.02	)		—
Total distributions declared to shareholders		$(0.17	)		$(0.18	)		$(0.21	)		$(0.16	)		$(0.10	)
Net asset value, end of period (x)		$13.11			$12.81			$11.86			$10.76			$10.92
Total return (%) (r)(s)(t)(x)		3.65	(n)		9.63			12.37			(0.09	)		10.21	(n)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		0.73	(a)		0.94			1.21			1.63			5.88	(a)
Expenses after expense reductions (f)		0.67	(a)		0.92			0.93			0.97			1.06	(a)
Net investment income (loss)		1.31	(a)(l)		1.77			1.76			1.79			1.80	(a)
Portfolio turnover		17	(n)		24			28			61			28	(n)
Net assets at end of period (000 omitted)		$67,323			$68,569			$45,799			$27,802			$5,966

See Notes to Financial Statements

Financial Highlights – continued

(a)	Annualized.

(c)	For the period from the commencement of the fund’s investment operations, December 5, 2013, through the stated period end.

(d)	Per share data is based on average shares outstanding.

(f)	Ratios do not reflect reductions from fees paid indirectly, if applicable.

(l)	Recognition of net investment income by the fund may be affected by the timing of the declaration of dividends by companies in which the fund invests and the actual annual net investment income ratio may differ.

(n)	Not annualized.

(r)	Certain expenses have been reduced without which performance would have been lower.

(s)	From time to time the fund may receive proceeds from litigation settlements, without which performance would be lower.

(t)	Total returns do not include any applicable sales charges.

(x)	The net asset values and total returns have been calculated on net assets which include adjustments made in accordance with U.S. generally accepted accounting principles required at period end for financial reporting purposes.

See Notes to Financial Statements

NOTES TO FINANCIAL STATEMENTS

(unaudited)

(1) Business and Organization

MFS Low Volatility Global Equity Fund (the fund) is a diversified series of MFS Series Trust I (the trust). The trust is organized as a Massachusetts business trust and is registered under the Investment Company Act of 1940, as amended, as an open-end management investment company.

(2) Significant Accounting Policies

General – The preparation of financial statements in conformity with U.S. generally accepted accounting principles requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of increases and decreases in net assets from operations during the reporting period. Actual results could differ from those estimates. In the preparation of these financial statements, management has evaluated subsequent events occurring after the date of the fund’s Statement of Assets and Liabilities through the date that the financial statements were issued. The fund invests in foreign securities. Investments in foreign securities are vulnerable to the effects of changes in the relative values of the local currency and the U.S. dollar and to the effects of changes in each country’s market, economic, industry, political, regulatory, geopolitical, and other conditions.

Investment Valuations – Equity securities, including restricted equity securities, are generally valued at the last sale or official closing price on their primary market or exchange as provided by a third-party pricing service. Equity securities, for which there were no sales reported that day, are generally valued at the last quoted daily bid quotation on their primary market or exchange as provided by a third-party pricing service. Short-term instruments with a maturity at issuance of 60 days or less may be valued at amortized cost, which approximates market value. Open-end investment companies are generally valued at net asset value per share. Securities and other assets generally valued on the basis of information from a third-party pricing service may also be valued at a broker/dealer bid quotation. Values obtained from third-party pricing services can utilize both transaction data and market information such as yield, quality,

Notes to Financial Statements (unaudited) – continued

coupon rate, maturity, type of issue, trading characteristics, and other market data. The values of foreign securities and other assets and liabilities expressed in foreign currencies are converted to U.S. dollars using the mean of bid and asked prices for rates provided by a third-party pricing service.

Various inputs are used in determining the value of the fund’s assets or liabilities. These inputs are categorized into three broad levels. In certain cases, the inputs used to measure fair value may fall into different levels of the fair value hierarchy. In such cases, an investment’s level within the fair value hierarchy is based on the lowest level of input that is significant to the fair value measurement. The fund’s assessment of the significance of a particular input to the fair value measurement in its entirety requires judgment, and considers factors specific to the investment. Level 1 includes unadjusted quoted prices in active markets for identical assets or liabilities. Level 2 includes other significant observable market-based inputs (including quoted prices for similar securities, interest rates, prepayment speed, and credit risk). Level 3 includes unobservable inputs, which may include the adviser’s own assumptions in determining

Notes to Financial Statements (unaudited) – continued

the fair value of investments. The following is a summary of the levels used as of February 28, 2018 in valuing the fund’s assets or liabilities:


Financial Instruments	Level 1		Level 2		Level 3		Total
Equity Securities:
United States		$79,216,235		$—		$—		$79,216,235
Japan		5,380,899		17,908,628		—		23,289,527
Canada		15,204,041		1,903,323		—		17,107,364
Switzerland		—		12,171,231		—		12,171,231
Hong Kong		—		8,779,995		—		8,779,995
United Kingdom		1,619,675		5,709,412		—		7,329,087
Taiwan		5,959,108		—		—		5,959,108
Germany		3,033,137		1,831,102		—		4,864,239
New Zealand		—		3,670,915		—		3,670,915
Other Countries		8,284,241		11,632,693		—		19,916,934
Mutual Funds		4,465,080		—		—		4,465,080
Total		$123,162,416		$63,607,299		$—		$186,769,715

For further information regarding security characteristics, see the Portfolio of Investments.

Of the level 2 investments presented above, equity investments amounting to $56,879,669 would have been considered level 1 investments at the beginning of the period. The primary reason for changes in the classifications between levels 1 and 2 occurs when foreign equity securities are fair valued using other observable market-based inputs in place of the closing exchange price due to events occurring after the close of the exchange or market on which the investment is principally traded. The fund’s foreign equity securities may often be valued using other observable market-based inputs. The fund’s policy is to recognize transfers between the levels as of the end of the period.

Notes to Financial Statements (unaudited) – continued

typically at least equal to the market value of the securities loaned. On loans collateralized by cash, the cash collateral is invested in a money market fund. The market value of the loaned securities is determined at the close of business of the fund and any additional required collateral is delivered to the fund on the next business day. State Street provides the fund with indemnification against Borrower default. In the event of Borrower default, State Street will, for the benefit of the fund, either purchase securities identical to those loaned or, when such purchase is commercially impracticable, pay the fund the market value of the loaned securities. In return, State Street assumes the fund’s rights to the related collateral. If the collateral value is less than the cost to purchase identical securities, State Street is responsible for the shortfall, but only to the extent that such shortfall is not due to a decline in collateral value resulting from collateral reinvestment for which the fund bears the risk of loss. At period end, the fund had investment securities on loan, all of which were classified as equity securities in the fund’s Portfolio of Investments, with a fair value of $2,838,106. The fair value of the fund’s investment securities on loan and a related liability of $2,957,531 for cash collateral received on securities loaned are both presented gross in the Statement of Assets and Liabilities. The collateral on securities loaned exceeded the value of securities on loan at period end. The liability for cash collateral for securities loaned is carried at fair value, which is categorized as level 2 within the fair value hierarchy. A portion of the income generated upon investment of the collateral is remitted to the Borrowers, and the remainder is allocated between the fund and the lending agent. On loans collateralized by U.S. Treasury and/or federal agency obligations, a fee is received from the Borrower, and is allocated between the fund and the lending agent. Income from securities lending is separately reported in the Statement of Operations. The dividend and interest income earned on the securities loaned is accounted for in the same manner as other dividend and interest income.

Investment Transactions and Income – Investment transactions are recorded on the trade date. Dividends received in cash are recorded on the ex-dividend date. Certain dividends from foreign securities will be recorded when the fund is informed of the dividend if such information is obtained subsequent to the ex-dividend date. Dividend payments received in additional securities are recorded on the ex-dividend date in an amount equal to the value of the security on such date.

Notes to Financial Statements (unaudited) – continued

Book/tax differences primarily relate to passive foreign investment companies and wash sale loss deferrals.

The tax character of distributions made during the current period will be determined at fiscal year end. The tax character of distributions declared to shareholders for the last fiscal year is as follows:


	Year ended 8/31/17
Ordinary income (including any short-term capital gains)		$1,436,284

Notes to Financial Statements (unaudited) – continued

The federal tax cost and the tax basis components of distributable earnings were as follows:


As of 2/28/18
Cost of investments	$165,980,842
Gross appreciation	24,524,763
Gross depreciation	(3,735,890	)
Net unrealized appreciation (depreciation)	$20,788,873

As of 8/31/17
Undistributed ordinary income	952,058
Capital loss carryforwards	(1,191,654	)
Other temporary differences	(55,128	)
Net unrealized appreciation (depreciation)	15,202,278

The aggregate cost above includes prior fiscal year end tax adjustments, if applicable.

As of August 31, 2017, the fund had capital loss carryforwards available to offset future realized gains. These net capital losses may be carried forward indefinitely and their character is retained as short-term and/or long-term losses. Such losses are characterized as follows:


Short-Term	$(970,650	)
Long-Term	(221,004	)
Total	$(1,191,654	)

Notes to Financial Statements (unaudited) – continued

convert to Class A shares approximately ten years after purchase. The fund’s distributions declared to shareholders as reported in the Statements of Changes in Net Assets are presented by class as follows:


	From net investment income
	Six months ended 2/28/18		Year ended 8/31/17
Class A		$109,037		$102,130
Class B		2,678		1,407
Class C		13,598		10,810
Class I		1,257,950		588,856
Class R1		498		288
Class R2		607		665
Class R3		1,045		901
Class R4		778		834
Class R6		859,766		730,393
Total		$2,245,957		$1,436,284

(3) Transactions with Affiliates

Investment Adviser – The fund has an investment advisory agreement with MFS to provide overall investment management and related administrative services and facilities to the fund. The management fee is computed daily and paid monthly at the following annual rates based on the fund’s average daily net assets:


Up to $1 billion	0.55	%
In excess of $1 billion and up to $2.5 billion	0.525	%
In excess of $2.5 billion	0.50	%

MFS has agreed in writing to reduce its management fee by a specified amount if certain MFS mutual fund assets exceed thresholds agreed to by MFS and the fund’s Board of Trustees. For the six months ended February 28, 2018, this management fee reduction amounted to $7,819, which is included in the reduction of total expenses in the Statement of Operations. The management fee incurred for the six months ended February 28, 2018 was equivalent to an annual effective rate of 0.54% of the fund’s average daily net assets.

The investment adviser has agreed in writing to pay a portion of the fund’s total annual operating expenses, excluding interest, taxes, extraordinary expenses, brokerage and transaction costs, and investment-related expenses, such that total fund operating expenses do not exceed the following rates annually of each class’s average daily net assets:


Classes
A	B		C		I		R1		R2		R3		R4		R6
0.99%		1.74%		1.74%		0.74%		1.74%		1.24%		0.99%		0.74%		0.68%

This written agreement will continue until modified by the fund’s Board of Trustees, but such agreement will continue at least until December 31, 2018. For the six months ended February 28, 2018, this reduction amounted to $44,318, which is included in the reduction of total expenses in the Statement of Operations.

Notes to Financial Statements (unaudited) – continued

Distributor – MFS Fund Distributors, Inc. (MFD), a wholly-owned subsidiary of MFS, as distributor, received $2,185 for the six months ended February 28, 2018, as its portion of the initial sales charge on sales of Class A shares of the fund.

The Board of Trustees has adopted a distribution plan for certain share classes pursuant to Rule 12b-1 of the Investment Company Act of 1940.

Distribution Plan Fee Table:


	Distribution Fee Rate (d)		Service Fee Rate (d)		Total Distribution Plan (d)		Annual Effective Rate (e)		Distribution and Service Fee
Class A		—		0.25%		0.25%		0.21%		$12,058
Class B		0.75%		0.25%		1.00%		1.00%		1,826
Class C		0.75%		0.25%		1.00%		1.00%		10,005
Class R1		0.75%		0.25%		1.00%		1.00%		348
Class R2		0.25%		0.25%		0.50%		0.50%		156
Class R3		—		0.25%		0.25%		0.25%		110
Total Distribution and Service Fees										$24,503

(d)

(e)

The annual effective rates represent actual fees incurred under the distribution plan for the six months ended February 28, 2018 based on each class’s average daily net assets. MFD has voluntarily agreed to rebate a portion of each class’s 0.25% service fee attributable to accounts for which MFD retains the 0.25% service fee except for accounts attributable to MFS or its affiliates’ seed money. For the six months ended February 28, 2018, this rebate amounted to $1,891 for Class A and is included in the reduction of total expenses in the Statement of Operations.


	Amount
Class A		$7
Class B		260
Class C		170

Notes to Financial Statements (unaudited) – continued

determined periodically under the supervision of the fund’s Board of Trustees. For the six months ended February 28, 2018, the fee was $3,180, which equated to 0.0035% annually of the fund’s average daily net assets. MFSC also receives payment from the fund for out-of-pocket expenses, sub-accounting and other shareholder servicing costs which may be paid to affiliated and unaffiliated service providers. Class R6 shares do not incur sub-accounting fees. For the six months ended February 28, 2018, these out-of-pocket expenses, sub-accounting and other shareholder servicing costs amounted to $40,123.

Other – This fund and certain other funds managed by MFS (the funds) have entered into a service agreement (the ISO Agreement) which provides for payment of fees solely by the funds to Tarantino LLC in return for the provision of services of an Independent Senior Officer (ISO) for the funds. Frank L. Tarantino serves as the ISO and is an officer of the funds and the sole member of Tarantino LLC. The funds can terminate the ISO Agreement with Tarantino LLC at any time under the terms of the ISO Agreement. For the six months ended February 28, 2018, the fee paid by the fund under this agreement was $156 and is included in “Miscellaneous” expense in the Statement of Operations. MFS has agreed to bear all expenses associated with office space, other administrative support, and supplies provided to the ISO.

On March 16, 2017, MFS purchased 2,133 shares of Class I for an aggregate amount of $25,873. On March 21, 2017, MFS purchased 412 shares of Class I for an aggregate amount of $4,989. On August 15, 2017, MFS redeemed 4,746 shares of Class C for an aggregate amount of $59,987. On September 20, 2017, MFS redeemed 2,847 shares of Class I for an aggregate amount of $36,499.

At February 28, 2018, MFS held approximately 89% of the outstanding shares of Class R1 and 100% of the outstanding shares of Class R2, Class R3, and Class R4, respectively.

Effective January 3, 2018, the adviser has voluntarily undertaken to reimburse the fund from its own resources on a quarterly basis for the cost of investment research

Notes to Financial Statements (unaudited) – continued

embedded in the cost of the fund’s securities trades. This agreement may be rescinded at any time. This reimbursement, if any, will be determined in arrears on a quarterly basis beginning with the quarter ending March 31, 2018.

(4) Portfolio Securities

For the six months ended February 28, 2018, purchases and sales of investments, other than short-term obligations, aggregated $30,843,016 and $35,326,593, respectively.

(5) Shares of Beneficial Interest

The fund’s Declaration of Trust permits the Trustees to issue an unlimited number of full and fractional shares of beneficial interest. Transactions in fund shares were as follows:


	Six months ended 2/28/18						Year ended 8/31/17
	Shares			Amount			Shares			Amount
Shares sold
Class A		88,807			$1,168,252			235,619			$2,835,638
Class B		2,105			27,943			6,560			79,744
Class C		39,250			514,123			76,350			907,914
Class I		1,502,759			19,752,213			7,672,302			93,687,604
Class R1		28			360			586			7,429
Class R2		—			—			181			2,100
Class R3		—			—			6,957			86,940
Class R6		673,357			8,768,940			2,104,117			26,035,765
		2,306,306			$30,231,831			10,102,672			$123,643,134

Shares issued to shareholders in reinvestment of distributions
Class A		8,347			$108,936			8,445			$102,071
Class B		206			2,678			116			1,407
Class C		1,047			13,598			893			10,751
Class I		92,293			1,202,997			41,894			518,156
Class R1		38			498			24			288
Class R2		45			607			55			665
Class R3		81			1,045			74			901
Class R4		60			778			69			834
Class R6		64,054			833,658			58,559			706,049
		166,171			$2,164,795			110,129			$1,341,122

Shares reacquired
Class A		(74,707	)		$(981,502	)		(154,676	)		$(1,860,946	)
Class B		(993	)		(12,774	)		(8,107	)		(95,574	)
Class C		(28,677	)		(375,754	)		(57,812	)		(703,973	)
Class I		(1,304,116	)		(17,076,330	)		(971,256	)		(11,953,174	)
Class R1		(1	)		(9	)		(1	)		(10	)
Class R2		—			—			(1,538	)		(18,712	)
Class R3		(7,000	)		(90,368	)		(3	)		(36	)
Class R6		(955,432	)		(12,468,741	)		(670,323	)		(8,400,532	)
		(2,370,926	)		$(31,005,478	)		(1,863,716	)		$(23,032,957	)

Notes to Financial Statements (unaudited) – continued


	Six months ended 2/28/18						Year ended 8/31/17
	Shares			Amount			Shares			Amount
Net change
Class A		22,447			$295,686			89,388			$1,076,763
Class B		1,318			17,847			(1,431	)		(14,423	)
Class C		11,620			151,967			19,431			214,692
Class I		290,936			3,878,880			6,742,940			82,252,586
Class R1		65			849			609			7,707
Class R2		45			607			(1,302	)		(15,947	)
Class R3		(6,919	)		(89,323	)		7,028			87,805
Class R4		60			778			69			834
Class R6		(218,021	)		(2,866,143	)		1,492,353			18,341,282
		101,551			$1,391,148			8,349,085			$101,951,299

Class T shares were not publicly available for sale during the period. Please see the fund’s prospectus for details.

(6) Line of Credit

The fund and certain other funds managed by MFS participate in a $1.25 billion unsecured committed line of credit, subject to a $1 billion sublimit, provided by a syndication of banks under a credit agreement. Borrowings may be made for temporary financing needs. Interest is charged to each fund, based on its borrowings, generally at a rate equal to the higher of the Overnight Federal Reserve funds rate or daily one month LIBOR plus an agreed upon spread. A commitment fee, based on the average daily, unused portion of the committed line of credit, is allocated among the participating funds at the end of each calendar quarter. In addition, the fund and other funds managed by MFS have established unsecured uncommitted borrowing arrangements with certain banks for temporary financing needs. Interest is charged to each fund, based on its borrowings, at a rate equal to the Overnight Federal Reserve funds rate plus an agreed upon spread. For the six months ended February 28, 2018, the fund’s commitment fee and interest expense were $501 and $0, respectively, and are included in “Miscellaneous” expense in the Statement of Operations.

(7) Investments in Affiliated Issuers


Affiliated Issuers				Beginning Shares/Par Amount		Acquisitions Shares/Par Amount		Dispositions Shares/Par Amount			Ending Shares/Par Amount
MFS Institutional Money Market Portfolio					1,955,613		17,131,097		(17,579,010	)		1,507,700

Affiliated Issuers	Realized Gain (Loss)			Change in Unrealized Appreciation (Depreciation)		Capital Gain Distributions		Dividend Income			Ending Value
MFS Institutional Money Market Portfolio		$(79	)		$59		$—		$7,261			$1,507,549

PROXY VOTING POLICIES AND INFORMATION

QUARTERLY PORTFOLIO DISCLOSURE

Public Reference Room

Securities and Exchange Commission

100 F Street, NE, Room 1580

Washington, D.C. 20549

FURTHER INFORMATION

INFORMATION ABOUT FUND CONTRACTS AND LEGAL CLAIMS

PROVISION OF FINANCIAL REPORTS AND SUMMARY PROSPECTUSES

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CONTACT

WEB SITE

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1-800-637-8255

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MAILING ADDRESS

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OVERNIGHT MAIL

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Canton, MA 02021-2809

Semiannual Report

February 28, 2018

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MFS® Low Volatility Equity Fund

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LVU-SEM

MFS® Low Volatility Equity Fund

CONTENTS


Letter from the Executive Chairman			1
Portfolio composition			2
Expense table			3
Portfolio of investments			5
Statement of assets and liabilities			10
Statement of operations			12
Statements of changes in net assets			13
Financial highlights			14
Notes to financial statements			20
Proxy voting policies and information			29
Quarterly portfolio disclosure			29
Further information			29
Information about fund contracts and legal claims			30
Provision of financial reports and summary prospectuses			30
Contact information back cover

The report is prepared for the general information of shareholders.

It is authorized for distribution to prospective investors only when preceded or accompanied by a current prospectus.

NOT FDIC INSURED • MAY LOSE VALUE • NO BANK GUARANTEE

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LETTER FROM THE EXECUTIVE CHAIRMAN

Dear Shareholders:

Rising bond yields have led to a measurable uptick in market volatility — a departure from the low-volatility environment that prevailed for much of 2017. In spite of this,

U.S. protectionism is also a growing concern, as investors fear that trade friction could disrupt the synchronized uptick in global growth.

Respectfully,

LOGO

Robert J. Manning

Executive Chairman

MFS Investment Management

April 13, 2018

The opinions expressed in this letter are subject to change and may not be relied upon for investment advice. No forecasts can be guaranteed.

PORTFOLIO COMPOSITION

Portfolio structure

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Top ten holdings
Waste Connections, Inc.			2.9%
PepsiCo, Inc.			2.8%
Amdocs Ltd.			2.8%
Johnson & Johnson			2.6%
Facebook, Inc., “A”			2.5%
Alphabet, Inc., “A”			2.5%
McDonald’s Corp.			2.3%
Cisco Systems, Inc.			2.3%
Costco Wholesale Corp.			2.2%
Eli Lilly & Co.			2.1%


Equity sectors
Financial Services			21.2%
Health Care			15.8%
Technology			12.0%
Consumer Staples			10.7%
Utilities & Communications			9.5%
Industrial Goods & Services			8.7%
Leisure			7.8%
Retailing			5.0%
Special Products & Services			4.7%
Energy			2.7%
Basic Materials			2.2%

From time to time Cash & Cash Equivalents may be negative due to timing of cash receipts.

Percentages are based on net assets as of February 28, 2018.

The portfolio is actively managed and current holdings may be different.

EXPENSE TABLE

Fund expenses borne by the shareholders during the period, September 1, 2017 through February 28, 2018

The example is based on an investment of $1,000 invested at the beginning of the period and held for the entire period September 1, 2017 through February 28, 2018.

Actual Expenses

Hypothetical Example for Comparison Purposes

Expense Table – continued


Share Class		Annualized Expense Ratio	Beginning Account Value 9/01/17	Ending Account Value 2/28/18	Expenses Paid During Period (p) 9/01/17-2/28/18
A	Actual	0.88%	$1,000.00	$1,048.11		$4.47
A	Hypothetical (h)	0.88%	$1,000.00	$1,020.43		$4.41
B	Actual	1.64%	$1,000.00	$1,044.11		$8.31
B	Hypothetical (h)	1.64%	$1,000.00	$1,016.66		$8.20
C	Actual	1.64%	$1,000.00	$1,044.27		$8.31
C	Hypothetical (h)	1.64%	$1,000.00	$1,016.66		$8.20
I	Actual	0.64%	$1,000.00	$1,049.41		$3.25
I	Hypothetical (h)	0.64%	$1,000.00	$1,021.62		$3.21
R1	Actual	1.64%	$1,000.00	$1,043.97		$8.31
R1	Hypothetical (h)	1.64%	$1,000.00	$1,016.66		$8.20
R2	Actual	1.14%	$1,000.00	$1,046.55		$5.78
R2	Hypothetical (h)	1.14%	$1,000.00	$1,019.14		$5.71
R3	Actual	0.89%	$1,000.00	$1,047.93		$4.52
R3	Hypothetical (h)	0.89%	$1,000.00	$1,020.38		$4.46
R4	Actual	0.64%	$1,000.00	$1,049.36		$3.25
R4	Hypothetical (h)	0.64%	$1,000.00	$1,021.62		$3.21
R6	Actual	0.55%	$1,000.00	$1,049.81		$2.80
R6	Hypothetical (h)	0.55%	$1,000.00	$1,022.07		$2.76

(h)	5% class return per year before expenses.

(p)

Notes to Expense Table

Each class with a Rule 12b-1 service fee is subject to a rebate of a portion of such fee. Such rebates are included in the expense ratios above and are outside of the expense limitation arrangement. For Class A shares, this rebate reduced the expense ratio above by 0.01%. See Note 3 in the Notes to Financial Statements for additional information.

PORTFOLIO OF INVESTMENTS

2/28/18 (unaudited)

The Portfolio of Investments is a complete list of all securities owned by your fund. It is categorized by broad-based asset classes.


Common Stocks - 100.3%
Issuer	Shares/Par		Value ($)
Aerospace - 5.7%
General Dynamics Corp.		2,935	$	652,891
Honeywell International, Inc.		9,405		1,421,189
Lockheed Martin Corp.		2,655		935,728
Northrop Grumman Corp.		4,042		1,414,862
United Technologies Corp.		4,695		632,604

			$	5,057,274
Alcoholic Beverages - 1.5%
Constellation Brands, Inc., “A”		6,019	$	1,296,974

Brokerage & Asset Managers - 1.5%
CME Group, Inc.		8,275	$	1,374,974

Business Services - 2.8%
Amdocs Ltd.		37,621	$	2,475,086

Cable TV - 0.7%
Comcast Corp., “A”		16,372	$	592,830

Computer Software - 2.2%
Blackbaud, Inc.		4,023	$	412,438
Intuit, Inc.		6,867		1,145,828
Oracle Corp.		7,156		362,594

			$	1,920,860
Consumer Products - 1.2%
Procter & Gamble Co.		13,401	$	1,052,247

Consumer Services - 1.9%
Bright Horizons Family Solutions, Inc. (a)		17,373	$	1,660,338

Containers - 0.4%
Berry Global Group, Inc. (a)		6,530	$	355,232

Electronics - 1.5%
Texas Instruments, Inc.		12,138	$	1,315,152

Energy - Independent - 0.6%
Occidental Petroleum Corp.		8,838	$	579,773

Portfolio of Investments (unaudited) – continued


Issuer	Shares/Par		Value ($)
Common Stocks - continued
Energy - Integrated - 0.7%
Exxon Mobil Corp.		8,072	$	611,373

Entertainment - 1.3%
Madison Square Garden Co., “A” (a)		4,555	$	1,112,331

Food & Beverages - 5.3%
General Mills, Inc.		21,763	$	1,100,120
Mondelez International, Inc.		14,830		651,037
PepsiCo, Inc.		22,571		2,476,716
Pinnacle Foods, Inc.		8,373		451,807

			$	4,679,680
Gaming & Lodging - 1.1%
Carnival Corp.		15,279	$	1,022,318

General Merchandise - 2.1%
Wal-Mart Stores, Inc.		20,274	$	1,824,863

Health Maintenance Organizations - 3.3%
Aetna, Inc.		2,468	$	436,984
Cigna Corp.		6,506		1,274,460
UnitedHealth Group, Inc.		5,249		1,187,114

			$	2,898,558
Insurance - 8.7%
Allstate Corp.		3,907	$	360,460
Aon PLC		8,659		1,215,031
Chubb Ltd.		4,726		670,714
Everest Re Group Ltd.		6,045		1,452,251
Hartford Financial Services Group, Inc.		18,187		961,183
Loews Corp.		23,850		1,176,520
Markel Corp. (a)		597		663,864
MetLife, Inc.		11,048		510,307
Travelers Cos., Inc.		4,691		652,049

			$	7,662,379
Internet - 5.5%
Alphabet, Inc., “A” (a)		1,976	$	2,181,346
Alphabet, Inc., “C” (a)		459		507,071
Facebook, Inc., “A” (a)		12,314		2,195,832

			$	4,884,249
Major Banks - 0.7%
PNC Financial Services Group, Inc.		3,946	$	622,126

Portfolio of Investments (unaudited) – continued


Issuer	Shares/Par		Value ($)
Common Stocks - continued
Medical & Health Technology & Services - 0.7%
Henry Schein, Inc. (a)		9,241	$	611,662

Medical Equipment - 5.9%
Becton, Dickinson and Co.		2,072	$	460,026
Cooper Cos., Inc.		3,131		721,758
Danaher Corp.		11,730		1,146,959
Medtronic PLC		15,067		1,203,703
Steris PLC		12,159		1,110,117
Stryker Corp.		3,295		534,317

			$	5,176,880
Network & Telecom - 2.8%
Cisco Systems, Inc.		44,428	$	1,989,486
Motorola Solutions, Inc.		4,599		488,184

			$	2,477,670
Oil Services - 1.3%
Schlumberger Ltd.		17,336	$	1,137,935

Other Banks & Diversified Financials - 3.5%
M&T Bank Corp.		4,522	$	858,456
Mastercard, Inc., “A”		5,481		963,341
U.S. Bancorp		9,835		534,631
Visa, Inc., “A”		5,776		710,101

			$	3,066,529
Pharmaceuticals - 6.0%
Eli Lilly & Co.		23,742	$	1,828,609
Johnson & Johnson		17,474		2,269,523
Pfizer, Inc.		20,069		728,705
Zoetis, Inc.		5,709		461,630

			$	5,288,467
Pollution Control - 2.9%
Waste Connections, Inc.		36,347	$	2,572,641

Printing & Publishing - 0.5%
Moody’s Corp.		2,940	$	490,627

Real Estate - 6.7%
AvalonBay Communities, Inc., REIT		6,435	$	1,003,989
Equity Lifestyle Properties, Inc., REIT		6,463		546,834
Mid-America Apartment Communities, Inc., REIT		6,471		555,341
Public Storage, Inc., REIT		4,681		910,174

Portfolio of Investments (unaudited) – continued


Issuer	Shares/Par		Value ($)
Common Stocks - continued
Real Estate - continued
Starwood Property Trust, Inc., REIT		83,544	$	1,691,766
Store Capital Corp., REIT		14,259		339,934
Sun Communities, Inc., REIT		10,173		890,748

			$	5,938,786
Restaurants - 4.2%
Aramark		12,601	$	525,588
McDonald’s Corp.		12,943		2,041,629
Starbucks Corp.		19,525		1,114,877

			$	3,682,094
Specialty Chemicals - 1.8%
Ecolab, Inc.		8,961	$	1,168,962
Praxair, Inc.		2,686		402,229

			$	1,571,191
Specialty Stores - 3.0%
Costco Wholesale Corp.		10,282	$	1,962,834
Home Depot, Inc.		3,576		651,797

			$	2,614,631
Telecommunications - Wireless - 0.5%
SBA Communications Corp., REIT (a)		2,718	$	427,460

Telephone Services - 0.8%
Verizon Communications, Inc.		14,474	$	690,989

Tobacco - 2.7%
Altria Group, Inc.		25,340	$	1,595,153
Philip Morris International, Inc.		7,930		821,152

			$	2,416,305
Utilities - Electric Power - 8.3%
Alliant Energy Corp.		16,569	$	640,392
American Electric Power Co., Inc.		6,947		455,584
DTE Energy Co.		9,472		954,588
Duke Energy Corp.		13,932		1,049,637
Exelon Corp.		8,938		331,063
NextEra Energy, Inc.		9,241		1,406,018
Pinnacle West Capital Corp.		4,123		317,306
WEC Energy Group, Inc.		15,591		934,213
Xcel Energy, Inc.		27,953		1,209,806

			$	7,298,607
Total Common Stocks (Identified Cost, $75,659,651)			$	88,461,091

Portfolio of Investments (unaudited) – continued


Investment Companies (h) - 0.8%
Issuer	Shares/Par		Value ($)
Money Market Funds - 0.8%
MFS Institutional Money Market Portfolio, 1.52% (v) (Identified Cost, $749,706)		749,822	$	749,747

Other Assets, Less Liabilities - (1.1)%				(977,284	)
Net Assets - 100.0%			$	88,233,554

(a)	Non-income producing security.

(h)

(v)	Affiliated issuer that is available only to investment companies managed by MFS. The rate quoted for the MFS Institutional Money Market Portfolio is the annualized seven-day yield of the fund at period end.

The following abbreviations are used in this report and are defined:

PLC

Public Limited Company

REIT

Real Estate Investment Trust

See Notes to Financial Statements

Financial Statements

STATEMENT OF ASSETS AND LIABILITIES

At 2/28/18 (unaudited)

This statement represents your fund’s balance sheet, which details the assets and liabilities comprising the total value of the fund.


Assets
Investments in unaffiliated issuers, at value (identified cost, $75,659,651)			$88,461,091
Investments in affiliated issuers, at value (identified cost, $749,706)			749,747
Receivables for
Fund shares sold			301,435
Dividends			151,208
Receivable from investment adviser			15,759
Other assets			50,416
Total assets			$89,729,656
Liabilities
Payables for fund shares reacquired			$1,438,911
Payable to affiliates
Shareholder servicing costs			18,760
Distribution and service fees			806
Payable for independent Trustees’ compensation			23
Accrued expenses and other liabilities			37,602
Total liabilities			$1,496,102
Net assets			$88,233,554
Net assets consist of
Paid-in capital			$74,814,831
Unrealized appreciation (depreciation)			12,801,481
Accumulated net realized gain (loss)			549,903
Undistributed net investment income			67,339
Net assets			$88,233,554
Shares of beneficial interest outstanding			6,243,226

Statement of Assets and Liabilities (unaudited) – continued


	Net assets		Shares outstanding		Net asset value per share (a)
Class A		$39,774,876		2,813,367		$14.14
Class B		2,158,758		153,001		14.11
Class C		14,049,313		998,575		14.07
Class I		24,142,853		1,706,061		14.15
Class R1		113,873		8,051		14.14
Class R2		77,673		5,470		14.20
Class R3		62,338		4,396		14.18
Class R4		61,727		4,358		14.16
Class R6		7,792,143		549,947		14.17

(a)

Maximum offering price per share was equal to the net asset value per share for all share classes, except for Class A, for which the maximum offering price per share was $15.00 [100 / 94.25 x $14.14]. On sales of $50,000 or more, the maximum offering price of Class A shares is reduced. A contingent deferred sales charge may be imposed on redemptions of Class A, Class B, and Class C shares. Redemption price per share was equal to the net asset value per share for Classes I, R1, R2, R3, R4, and R6. Net asset value per share is calculated using actual net assets and shares outstanding rather than amounts that have been rounded for presentation purposes.

See Notes to Financial Statements

Financial Statements

STATEMENT OF OPERATIONS

Six months ended 2/28/18 (unaudited)

This statement describes how much your fund earned in investment income and accrued in expenses. It also describes any gains and/or losses generated by fund operations.


Net investment income (loss)
Income
Dividends	$928,298
Dividends from affiliated issuers	2,736
Foreign taxes withheld	(1,477	)
Total investment income	$929,557
Expenses
Management fee	$218,468
Distribution and service fees	127,103
Shareholder servicing costs	47,200
Administrative services fee	11,514
Independent Trustees’ compensation	1,356
Custodian fee	4,764
Shareholder communications	9,805
Audit and tax fees	24,570
Legal fees	515
Registration fees	62,931
Miscellaneous	8,558
Total expenses	$516,784
Reduction of expenses by investment adviser and distributor	(114,685	)
Net expenses	$402,099
Net investment income (loss)	$527,458
Realized and unrealized gain (loss)
Realized gain (loss) (identified cost basis)
Unaffiliated issuers	$1,930,815
Affiliated issuers	(148	)
Net realized gain (loss)	$1,930,667
Change in unrealized appreciation (depreciation)
Unaffiliated issuers	$1,574,102
Affiliated issuers	41
Net unrealized gain (loss)	$1,574,143
Net realized and unrealized gain (loss)	$3,504,810
Change in net assets from operations	$4,032,268

See Notes to Financial Statements

Financial Statements

STATEMENTS OF CHANGES IN NET ASSETS

These statements describe the increases and/or decreases in net assets resulting from operations, any distributions, and any shareholder transactions.


	Six months ended			Year ended
	2/28/18			8/31/17
Change in net assets	(unaudited)
From operations
Net investment income (loss)		$527,458			$787,278
Net realized gain (loss)		1,930,667			343,998
Net unrealized gain (loss)		1,574,143			6,210,716
Change in net assets from operations		$4,032,268			$7,341,992
Distributions declared to shareholders
From net investment income		$(639,876	)		$(761,769	)
From net realized gain		(1,151,155	)		(134,785	)
Total distributions declared to shareholders		$(1,791,031	)		$(896,554	)
Change in net assets from fund share transactions		$3,292,251			$16,852,555
Total change in net assets		$5,533,488			$23,297,993
Net assets
At beginning of period		82,700,066			59,402,073
At end of period (including undistributed net investment income of $67,339 and $179,757, respectively)		$88,233,554			$82,700,066

See Notes to Financial Statements

Financial Statements

FINANCIAL HIGHLIGHTS


	Six months ended 2/28/18			Year ended
Class A	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14 (c)
	(unaudited)
Net asset value, beginning of period		$13.77			$12.56			$11.12			$10.82			$10.00
Income (loss) from investment operations
Net investment income (loss) (d)		$0.09			$0.16			$0.15			$0.14			$0.11
Net realized and unrealized gain (loss)		0.58			1.23			1.49			0.30	(g)		0.77
Total from investment operations		$0.67			$1.39			$1.64			$0.44			$0.88
Less distributions declared to shareholders
From net investment income		$(0.11	)		$(0.15	)		$(0.11	)		$(0.13	)		$(0.06	)
From net realized gain		(0.19	)		(0.03	)		(0.09	)		(0.01	)		—
Total distributions declared to shareholders		$(0.30	)		$(0.18	)		$(0.20	)		$(0.14	)		$(0.06	)
Net asset value, end of period (x)		$14.14			$13.77			$12.56			$11.12			$10.82
Total return (%) (r)(s)(t)(x)		4.81	(n)		11.18			14.87			4.01			8.82	(n)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.15	(a)		1.33			1.65			2.72			4.45	(a)
Expenses after expense reductions (f)		0.88	(a)		1.16			1.19			1.18			1.15	(a)
Net investment income (loss)		1.24	(a)		1.19			1.25			1.22			1.40	(a)
Portfolio turnover		15	(n)		36			38			33			30	(n)
Net assets at end of period (000 omitted)		$39,775			$39,568			$29,508			$11,267			$1,154

See Notes to Financial Statements

Financial Highlights – continued


	Six months ended 2/28/18			Year ended
Class B	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14 (c)
	(unaudited)
Net asset value, beginning of period		$13.74			$12.53			$11.10			$10.81			$10.00
Income (loss) from investment operations
Net investment income (loss) (d)		$0.03			$0.06			$0.06			$0.05			$0.04
Net realized and unrealized gain (loss)		0.58			1.23			1.48			0.30	(g)		0.78
Total from investment operations		$0.61			$1.29			$1.54			$0.35			$0.82
Less distributions declared to shareholders
From net investment income		$(0.05	)		$(0.05	)		$(0.02	)		$(0.05	)		$(0.01	)
From net realized gain		(0.19	)		(0.03	)		(0.09	)		(0.01	)		—
Total distributions declared to shareholders		$(0.24	)		$(0.08	)		$(0.11	)		$(0.06	)		$(0.01	)
Net asset value, end of period (x)		$14.11			$13.74			$12.53			$11.10			$10.81
Total return (%) (r)(s)(t)(x)		4.41	(n)		10.36			13.96			3.20			8.23	(n)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.90	(a)		2.08			2.42			3.79			5.75	(a)
Expenses after expense reductions (f)		1.64	(a)		1.92			1.95			1.95			1.93	(a)
Net investment income (loss)		0.48	(a)		0.43			0.49			0.43			0.46	(a)
Portfolio turnover		15	(n)		36			38			33			30	(n)
Net assets at end of period (000 omitted)		$2,159			$2,081			$1,885			$717			$170

	Six months ended 2/28/18			Year ended
Class C	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14 (c)
	(unaudited)
Net asset value, beginning of period		$13.70			$12.50			$11.09			$10.80			$10.00
Income (loss) from investment operations
Net investment income (loss) (d)		$0.03			$0.06			$0.06			$0.05			$0.04
Net realized and unrealized gain (loss)		0.58			1.23			1.48			0.30	(g)		0.79
Total from investment operations		$0.61			$1.29			$1.54			$0.35			$0.83
Less distributions declared to shareholders
From net investment income		$(0.05	)		$(0.06	)		$(0.04	)		$(0.05	)		$(0.03	)
From net realized gain		(0.19	)		(0.03	)		(0.09	)		(0.01	)		—
Total distributions declared to shareholders		$(0.24	)		$(0.09	)		$(0.13	)		$(0.06	)		$(0.03	)
Net asset value, end of period (x)		$14.07			$13.70			$12.50			$11.09			$10.80
Total return (%) (r)(s)(t)(x)		4.43	(n)		10.36			13.91			3.23			8.27	(n)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.90	(a)		2.08			2.31			3.73			5.39	(a)
Expenses after expense reductions (f)		1.64	(a)		1.92			1.95			1.95			1.93	(a)
Net investment income (loss)		0.49	(a)		0.43			0.48			0.43			0.48	(a)
Portfolio turnover		15	(n)		36			38			33			30	(n)
Net assets at end of period (000 omitted)		$14,049			$12,422			$9,977			$1,564			$421

See Notes to Financial Statements

Financial Highlights – continued


	Six months ended 2/28/18			Year ended
Class I	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14 (c)
	(unaudited)
Net asset value, beginning of period		$13.78			$12.57			$11.14			$10.84			$10.00
Income (loss) from investment operations
Net investment income (loss) (d)		$0.11			$0.19			$0.18			$0.16			$0.11
Net realized and unrealized gain (loss)		0.58			1.23			1.48			0.30	(g)		0.80
Total from investment operations		$0.69			$1.42			$1.66			$0.46			$0.91
Less distributions declared to shareholders
From net investment income		$(0.13	)		$(0.18	)		$(0.14	)		$(0.15	)		$(0.07	)
From net realized gain		(0.19	)		(0.03	)		(0.09	)		(0.01	)		—
Total distributions declared to shareholders		$(0.32	)		$(0.21	)		$(0.23	)		$(0.16	)		$(0.07	)
Net asset value, end of period (x)		$14.15			$13.78			$12.57			$11.14			$10.84
Total return (%) (r)(s)(t)(x)		4.94	(n)		11.44			15.05			4.20			9.09	(n)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		0.90	(a)		1.07			1.20			2.53			4.72	(a)
Expenses after expense reductions (f)		0.64	(a)		0.92			0.95			0.95			0.93	(a)
Net investment income (loss)		1.49	(a)		1.47			1.51			1.36			1.43	(a)
Portfolio turnover		15	(n)		36			38			33			30	(n)
Net assets at end of period (000 omitted)		$24,143			$21,814			$16,123			$964			$177

	Six months ended 2/28/18			Year ended
Class R1	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14 (c)
	(unaudited)
Net asset value, beginning of period		$13.77			$12.57			$11.12			$10.82			$10.00
Income (loss) from investment operations
Net investment income (loss) (d)		$0.03			$0.05			$0.06			$0.04			$0.03
Net realized and unrealized gain (loss)		0.58			1.24			1.49			0.31	(g)		0.80
Total from investment operations		$0.61			$1.29			$1.55			$0.35			$0.83
Less distributions declared to shareholders
From net investment income		$(0.05	)		$(0.06	)		$(0.01	)		$(0.04	)		$(0.01	)
From net realized gain		(0.19	)		(0.03	)		(0.09	)		(0.01	)		—
Total distributions declared to shareholders		$(0.24	)		$(0.09	)		$(0.10	)		$(0.05	)		$(0.01	)
Net asset value, end of period (x)		$14.14			$13.77			$12.57			$11.12			$10.82
Total return (%) (r)(s)(t)(x)		4.40	(n)		10.33			13.96			3.18			8.30	(n)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.90	(a)		2.07			2.56			4.18			5.92	(a)
Expenses after expense reductions (f)		1.64	(a)		1.91			1.95			1.95			1.93	(a)
Net investment income (loss)		0.48	(a)		0.41			0.48			0.39			0.40	(a)
Portfolio turnover		15	(n)		36			38			33			30	(n)
Net assets at end of period (000 omitted)		$114			$108			$57			$112			$108

See Notes to Financial Statements

Financial Highlights – continued


	Six months ended 2/28/18			Year ended
Class R2	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14 (c)
	(unaudited)
Net asset value, beginning of period		$13.83			$12.61			$11.13			$10.83			$10.00
Income (loss) from investment operations
Net investment income (loss) (d)		$0.07			$0.12			$0.12			$0.10			$0.07
Net realized and unrealized gain (loss)		0.58			1.25			1.49			0.30	(g)		0.80
Total from investment operations		$0.65			$1.37			$1.61			$0.40			$0.87
Less distributions declared to shareholders
From net investment income		$(0.09	)		$(0.12	)		$(0.04	)		$(0.09	)		$(0.04	)
From net realized gain		(0.19	)		(0.03	)		(0.09	)		(0.01	)		—
Total distributions declared to shareholders		$(0.28	)		$(0.15	)		$(0.13	)		$(0.10	)		$(0.04	)
Net asset value, end of period (x)		$14.20			$13.83			$12.61			$11.13			$10.83
Total return (%) (r)(s)(t)(x)		4.66	(n)		10.93			14.57			3.69			8.69	(n)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.40	(a)		1.58			2.07			3.68			5.42	(a)
Expenses after expense reductions (f)		1.14	(a)		1.42			1.45			1.45			1.43	(a)
Net investment income (loss)		0.98	(a)		0.91			0.98			0.89			0.90	(a)
Portfolio turnover		15	(n)		36			38			33			30	(n)
Net assets at end of period (000 omitted)		$78			$74			$53			$113			$109

	Six months ended 2/28/18			Year ended
Class R3	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14 (c)
	(unaudited)
Net asset value, beginning of period		$13.81			$12.59			$11.14			$10.83			$10.00
Income (loss) from investment operations
Net investment income (loss) (d)		$0.09			$0.15			$0.15			$0.13			$0.09
Net realized and unrealized gain (loss)		0.58			1.25			1.48			0.31	(g)		0.79
Total from investment operations		$0.67			$1.40			$1.63			$0.44			$0.88
Less distributions declared to shareholders
From net investment income		$(0.11	)		$(0.15	)		$(0.09	)		$(0.12	)		$(0.05	)
From net realized gain		(0.19	)		(0.03	)		(0.09	)		(0.01	)		—
Total distributions declared to shareholders		$(0.30	)		$(0.18	)		$(0.18	)		$(0.13	)		$(0.05	)
Net asset value, end of period (x)		$14.18			$13.81			$12.59			$11.14			$10.83
Total return (%) (r)(s)(t)(x)		4.79	(n)		11.22			14.72			4.04			8.84	(n)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.15	(a)		1.33			1.82			3.43			5.17	(a)
Expenses after expense reductions (f)		0.89	(a)		1.17			1.20			1.20			1.18	(a)
Net investment income (loss)		1.23	(a)		1.18			1.23			1.14			1.15	(a)
Portfolio turnover		15	(n)		36			38			33			30	(n)
Net assets at end of period (000 omitted)		$62			$59			$53			$113			$109

See Notes to Financial Statements

Financial Highlights – continued


	Six months ended 2/28/18			Year ended
Class R4	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14 (c)
	(unaudited)
Net asset value, beginning of period		$13.79			$12.58			$11.14			$10.84			$10.00
Income (loss) from investment operations
Net investment income (loss) (d)		$0.11			$0.19			$0.17			$0.16			$0.11
Net realized and unrealized gain (loss)		0.58			1.23			1.49			0.30	(g)		0.80
Total from investment operations		$0.69			$1.42			$1.66			$0.46			$0.91
Less distributions declared to shareholders
From net investment income		$(0.13	)		$(0.18	)		$(0.13	)		$(0.15	)		$(0.07	)
From net realized gain		(0.19	)		(0.03	)		(0.09	)		(0.01	)		—
Total distributions declared to shareholders		$(0.32	)		$(0.21	)		$(0.22	)		$(0.16	)		$(0.07	)
Net asset value, end of period (x)		$14.16			$13.79			$12.58			$11.14			$10.84
Total return (%) (r)(s)(t)(x)		4.94	(n)		11.42			15.08			4.20			9.09	(n)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		0.90	(a)		1.08			1.57			3.18			4.92	(a)
Expenses after expense reductions (f)		0.64	(a)		0.92			0.95			0.95			0.93	(a)
Net investment income (loss)		1.50	(a)		1.42			1.48			1.39			1.40	(a)
Portfolio turnover		15	(n)		36			38			33			30	(n)
Net assets at end of period (000 omitted)		$62			$59			$53			$114			$109

	Six months ended 2/28/18			Year ended
Class R6	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14 (c)
	(unaudited)
Net asset value, beginning of period		$13.80			$12.58			$11.14			$10.84			$10.00
Income (loss) from investment operations
Net investment income (loss) (d)		$0.11			$0.18			$0.18			$0.16			$0.11
Net realized and unrealized gain (loss)		0.58			1.27			1.50			0.30	(g)		0.80
Total from investment operations		$0.69			$1.45			$1.68			$0.46			$0.91
Less distributions declared to shareholders
From net investment income		$(0.13	)		$(0.20	)		$(0.15	)		$(0.15	)		$(0.07	)
From net realized gain		(0.19	)		(0.03	)		(0.09	)		(0.01	)		—
Total distributions declared to shareholders		$(0.32	)		$(0.23	)		$(0.24	)		$(0.16	)		$(0.07	)
Net asset value, end of period (x)		$14.17			$13.80			$12.58			$11.14			$10.84
Total return (%) (r)(s)(t)(x)		4.98	(n)		11.61			15.21			4.22			9.11	(n)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		0.81	(a)		0.97			1.36			3.14			4.90	(a)
Expenses after expense reductions (f)		0.55	(a)		0.78			0.88			0.91			0.91	(a)
Net investment income (loss)		1.58	(a)		1.38			1.53			1.43			1.42	(a)
Portfolio turnover		15	(n)		36			38			33			30	(n)
Net assets at end of period (000 omitted)		$7,792			$6,515			$1,693			$1,593			$1,527

See Notes to Financial Statements

Financial Highlights – continued

(a)	Annualized.

(c)	For the period from the commencement of the fund’s investment operations, December 5, 2013, through the stated period end.

(d)	Per share data is based on average shares outstanding.

(f)	Ratios do not reflect reductions from fees paid indirectly, if applicable.

(g)	The per share amount varies from the net realized and unrealized gain/loss for the period because of the timing of sales of fund shares and the per share amount of realized and unrealized gains and losses at such time.

(n)	Not annualized.

(r)	Certain expenses have been reduced without which performance would have been lower.

(s)	From time to time the fund may receive proceeds from litigation settlements, without which performance would be lower.

(t)	Total returns do not include any applicable sales charges.

(x)	The net asset values and total returns have been calculated on net assets which include adjustments made in accordance with U.S. generally accepted accounting principles required at period end for financial reporting purposes.

See Notes to Financial Statements

NOTES TO FINANCIAL STATEMENTS

(unaudited)

(1) Business and Organization

MFS Low Volatility Equity Fund (the fund) is a diversified series of MFS Series Trust I (the trust). The trust is organized as a Massachusetts business trust and is registered under the Investment Company Act of 1940, as amended, as an open-end management investment company.

(2) Significant Accounting Policies

Notes to Financial Statements (unaudited) – continued

the fair value of investments. The following is a summary of the levels used as of February 28, 2018 in valuing the fund’s assets or liabilities:


Financial Instruments	Level 1		Level 2		Level 3		Total
Equity Securities		$88,461,091		$—		$—		$88,461,091
Mutual Funds		749,747		—		—		749,747
Total		$89,210,838		$—		$—		$89,210,838

For further information regarding security characteristics, see the Portfolio of Investments.

Notes to Financial Statements (unaudited) – continued

to reflect their tax character. These adjustments have no impact on net assets or net asset value per share. Temporary differences which arise from recognizing certain items of income, expense, gain or loss in different periods for financial statement and tax purposes will reverse at some time in the future. Distributions in excess of net investment income or net realized gains are temporary overdistributions for financial statement purposes resulting from differences in the recognition or classification of income or distributions for financial statement and tax purposes.

Book/tax differences primarily relate to wash sale loss deferrals and treating a portion of the proceeds from redemptions as a distribution for tax purposes.


	Year ended 8/31/17
Ordinary income (including any short-term capital gains)		$867,018
Long-term capital gains		29,536
Total distributions		$896,554

The federal tax cost and the tax basis components of distributable earnings were as follows:


As of 2/28/18
Cost of investments	$76,411,036
Gross appreciation	14,098,238
Gross depreciation	(1,298,436	)
Net unrealized appreciation (depreciation)	$12,799,802

As of 8/31/17
Undistributed ordinary income	179,757
Undistributed long-term capital gain	91,202
Post-October capital loss deferral	(89,950	)
Net unrealized appreciation (depreciation)	10,996,477

The aggregate cost above includes prior fiscal year end tax adjustments, if applicable.

Notes to Financial Statements (unaudited) – continued


	From net investment income				From net realized gain
	Six months ended 2/28/18		Year ended 8/31/17		Six months ended 2/28/18		Year ended 8/31/17
Class A		$302,657		$401,351		$520,876		$72,819
Class B		7,948		8,063		28,574		4,185
Class C		47,786		50,551		170,155		22,638
Class I		212,718		275,528		330,158		31,512
Class R1		404		375		1,471		129
Class R2		478		501		1,003		119
Class R3		456		638		799		120
Class R4		534		776		798		120
Class R6		66,895		23,986		97,321		3,143
Total		$639,876		$761,769		$1,151,155		$134,785

(3) Transactions with Affiliates


Up to $1 billion			0.50%
In excess of $1 billion and up to $2.5 billion			0.475%
In excess of $2.5 billion			0.45%

MFS has agreed in writing to reduce its management fee by a specified amount if certain MFS mutual fund assets exceed thresholds agreed to by MFS and the fund’s Board of Trustees. For the six months ended February 28, 2018, this management fee reduction amounted to $3,758, which is included in the reduction of total expenses in the Statement of Operations. The management fee incurred for the six months ended February 28, 2018 was equivalent to an annual effective rate of 0.49% of the fund’s average daily net assets.


							Classes
A	B		C		I		R1		R2		R3		R4		R6
0.89%		1.64%		1.64%		0.64%		1.64%		1.14%		0.89%		0.64%		0.57%

This written agreement will continue until modified by the fund’s Board of Trustees, but such agreement will continue at least until December 31, 2018. For the six months ended February 28, 2018, this reduction amounted to $108,938, which is included in the reduction of total expenses in the Statement of Operations.

Notes to Financial Statements (unaudited) – continued

Distributor – MFS Fund Distributors, Inc. (MFD), a wholly-owned subsidiary of MFS, as distributor, received $12,121 for the six months ended February 28, 2018, as its portion of the initial sales charge on sales of Class A shares of the fund.

The Board of Trustees has adopted a distribution plan for certain share classes pursuant to Rule 12b-1 of the Investment Company Act of 1940.

Distribution Plan Fee Table:


	Distribution Fee Rate (d)		Service Fee Rate (d)		Total Distribution Plan (d)		Annual Effective Rate (e)		Distribution and Service Fee
Class A		—		0.25%		0.25%		0.24%		$50,369
Class B		0.75%		0.25%		1.00%		1.00%		10,808
Class C		0.75%		0.25%		1.00%		1.00%		65,098
Class R1		0.75%		0.25%		1.00%		1.00%		560
Class R2		0.25%		0.25%		0.50%		0.50%		192
Class R3		—		0.25%		0.25%		0.25%		76
Total Distribution and Service Fees										$127,103

(d)

(e)

The annual effective rates represent actual fees incurred under the distribution plan for the six months ended February 28, 2018 based on each class’s average daily net assets. MFD has voluntarily agreed to rebate a portion of each class’s 0.25% service fee attributable to accounts for which MFD retains the 0.25% service fee except for accounts attributable to MFS or its affiliates’ seed money. For the six months ended February 28, 2018, this rebate amounted to $1,981, $1, and $7 for Class A, Class B, and Class C, respectively, and is included in the reduction of total expenses in the Statement of Operations.


	Amount
Class A		$389
Class B		3,163
Class C		691

Notes to Financial Statements (unaudited) – continued

six months ended February 28, 2018, the fee was $6,858, which equated to 0.0157% annually of the fund’s average daily net assets. MFSC also receives payment from the fund for out-of- pocket expenses, sub-accounting and other shareholder servicing costs which may be paid to affiliated and unaffiliated service providers. Class R6 shares do not incur sub-accounting fees. For the six months ended February 28, 2018, these out-of-pocket expenses, sub-accounting and other shareholder servicing costs amounted to $40,342.

Other – This fund and certain other funds managed by MFS (the funds) have entered into a service agreement (the ISO Agreement) which provides for payment of fees solely by the funds to Tarantino LLC in return for the provision of services of an Independent Senior Officer (ISO) for the funds. Frank L. Tarantino serves as the ISO and is an officer of the funds and the sole member of Tarantino LLC. The funds can terminate the ISO Agreement with Tarantino LLC at any time under the terms of the ISO Agreement. For the six months ended February 28, 2018, the fee paid by the fund under this agreement was $72 and is included in “Miscellaneous” expense in the Statement of Operations. MFS has agreed to bear all expenses associated with office space, other administrative support, and supplies provided to the ISO.

On March 16, 2017, MFS purchased 2,545 shares of Class I for an aggregate amount of $33,844. On March 21, 2017, MFS redeemed 412 shares of Class I for an aggregate amount of $5,438.

At February 28, 2018, MFS held approximately 58%, 79%, 99%, and 100% of the outstanding shares of Class R1, Class R2, Class R3, and Class R4, respectively.

Notes to Financial Statements (unaudited) – continued

(4) Portfolio Securities

For the six months ended February 28, 2018, purchases and sales of investments, other than short-term obligations, aggregated $16,230,448 and $13,338,947, respectively.

(5) Shares of Beneficial Interest

The fund’s Declaration of Trust permits the Trustees to issue an unlimited number of full and fractional shares of beneficial interest. Transactions in fund shares were as follows:


	Six months ended 2/28/18						Year ended 8/31/17
	Shares			Amount			Shares			Amount
Shares sold
Class A		368,255			$5,223,318			1,456,499			$18,899,873
Class B		14,778			212,077			41,150			534,770
Class C		163,130			2,327,211			356,503			4,664,725
Class I		403,901			5,737,784			1,624,156			21,194,572
Class R1		89			1,260			3,284			44,177
Class R2		1			13			1,141			15,604
Class R3		45			642			19			260
Class R6		160,904			2,282,729			434,316			5,859,230
		1,111,103			$15,785,034			3,917,068			$51,213,211

Shares issued to shareholders in reinvestment of distributions
Class A		57,806			$822,179			36,525			$473,635
Class B		2,562			36,522			951			12,248
Class C		15,312			217,670			5,654			72,738
Class I		38,160			542,804			23,535			307,040
Class R1		131			1,875			38			504
Class R2		103			1,481			48			620
Class R3		88			1,254			59			757
Class R4		93			1,332			69			895
Class R6		9,430			134,293			262			3,416
		123,685			$1,759,410			67,141			$871,853

Shares reacquired
Class A		(487,108	)		$(6,948,359	)		(968,834	)		$(12,572,950	)
Class B		(15,859	)		(224,359	)		(41,062	)		(535,569	)
Class C		(86,657	)		(1,230,950	)		(253,515	)		(3,323,190	)
Class I		(319,018	)		(4,536,521	)		(1,347,574	)		(17,546,911	)
Class R1		(3	)		(41	)		(22	)		(303	)
Class R2		(2	)		(32	)		(1	)		(10	)
Class R3		—			—			(1	)		(4	)
Class R6		(92,580	)		(1,311,931	)		(96,998	)		(1,253,572	)
		(1,001,227	)		$(14,252,193	)		(2,708,007	)		$(35,232,509	)

Notes to Financial Statements (unaudited) – continued


	Six months ended 2/28/18						Year ended 8/31/17
	Shares			Amount			Shares		Amount
Net change
Class A		(61,047	)		$(902,862	)		524,190		$6,800,558
Class B		1,481			24,240			1,039		11,449
Class C		91,785			1,313,931			108,642		1,414,273
Class I		123,043			1,744,067			300,117		3,954,701
Class R1		217			3,094			3,300		44,378
Class R2		102			1,462			1,188		16,214
Class R3		133			1,896			77		1,013
Class R4		93			1,332			69		895
Class R6		77,754			1,105,091			337,580		4,609,074
		233,561			$3,292,251			1,276,202		$16,852,555

Class T shares were not publicly available for sale during the period. Please see the fund’s prospectus for details.

(6) Line of Credit

The fund and certain other funds managed by MFS participate in a $1.25 billion unsecured committed line of credit, subject to a $1 billion sublimit, provided by a syndication of banks under a credit agreement. Borrowings may be made for temporary financing needs. Interest is charged to each fund, based on its borrowings, generally at a rate equal to the higher of the Overnight Federal Reserve funds rate or daily one month LIBOR plus an agreed upon spread. A commitment fee, based on the average daily, unused portion of the committed line of credit, is allocated among the participating funds at the end of each calendar quarter. In addition, the fund and other funds managed by MFS have established unsecured uncommitted borrowing arrangements with certain banks for temporary financing needs. Interest is charged to each fund, based on its borrowings, at a rate equal to the Overnight Federal Reserve funds rate plus an agreed upon spread. For the six months ended February 28, 2018, the fund’s commitment fee and interest expense were $268 and $0, respectively, and are included in “Miscellaneous” expense in the Statement of Operations.

(7) Investments in Affiliated Issuers


Affiliated Issuers				Beginning Shares/Par Amount		Acquisitions Shares/Par Amount		Dispositions Shares/Par Amount			Ending Shares/Par Amount
MFS Institutional Money Market Portfolio					631,939		8,184,896		(8,067,013	)		749,822

Affiliated Issuers	Realized Gain (Loss)			Change in Unrealized Appreciation (Depreciation)		Capital Gain Distributions		Dividend Income			Ending Value
MFS Institutional Money Market Portfolio		$(148	)		$41		$—		$2,736			$749,747

PROXY VOTING POLICIES AND INFORMATION

QUARTERLY PORTFOLIO DISCLOSURE

Public Reference Room

Securities and Exchange Commission

100 F Street, NE, Room 1580

Washington, D.C. 20549

FURTHER INFORMATION

INFORMATION ABOUT FUND CONTRACTS AND LEGAL CLAIMS

PROVISION OF FINANCIAL REPORTS AND SUMMARY PROSPECTUSES

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CONTACT

WEB SITE

mfs.com

MFS TALK

1-800-637-8255

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ACCOUNT SERVICE AND LITERATURE

Shareholders

1-800-225-2606

Financial advisors

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MAILING ADDRESS

MFS Service Center, Inc.

P.O. Box 55824

Boston, MA 02205-5824

OVERNIGHT MAIL

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c/o DST Asset Manager Solutions, Inc.

30 Dan Road

Canton, MA 02021-2809

Semiannual Report

February 28, 2018

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MFS® New Discovery Fund

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NDF-SEM

MFS® New Discovery Fund

CONTENTS


Letter from the Executive Chairman			1
Portfolio composition			2
Expense table			3
Portfolio of investments			5
Statement of assets and liabilities			11
Statement of operations			13
Statements of changes in net assets			14
Financial highlights			15
Notes to financial statements			22
Proxy voting policies and information			34
Quarterly portfolio disclosure			34
Further information			34
Information about fund contracts and legal claims			35
Provision of financial reports and summary prospectuses			35
Contact information back cover

The report is prepared for the general information of shareholders.

It is authorized for distribution to prospective investors only when preceded or accompanied by a current prospectus.

NOT FDIC INSURED • MAY LOSE VALUE • NO BANK GUARANTEE

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LETTER FROM THE EXECUTIVE CHAIRMAN

Dear Shareholders:

Rising bond yields have led to a measurable uptick in market volatility — a departure from the low-volatility environment that prevailed for much of 2017. In spite of this,

U.S. protectionism is also a growing concern, as investors fear that trade friction could disrupt the synchronized uptick in global growth.

Respectfully,

LOGO

Robert J. Manning

Executive Chairman

MFS Investment Management

April 13, 2018

The opinions expressed in this letter are subject to change and may not be relied upon for investment advice. No forecasts can be guaranteed.

PORTFOLIO COMPOSITION

Portfolio structure

LOGO


Top ten holdings
U.S. Foods Holding Corp.			1.9%
Bright Horizons Family Solutions, Inc.			1.9%
LogMeIn, Inc.			1.8%
NICE Systems Ltd., ADR			1.7%
Berry Plastics Group, Inc.			1.7%
Zendesk, Inc.			1.6%
Kar Auction Services, Inc.			1.6%
Performance Food Group Co.			1.5%
ICON PLC			1.4%
Twilio, Inc., “A”			1.4%


Equity sectors
Technology			29.1%
Health Care			19.4%
Special Products & Services			9.2%
Industrial Goods & Services			9.0%
Financial Services			7.7%
Autos & Housing			7.1%
Basic Materials			7.0%
Leisure			5.9%
Consumer Staples			1.6%
Energy			0.6%
Retailing			0.6%
Transportation			0.3%

Percentages are based on net assets as of February 28, 2018.

The portfolio is actively managed and current holdings may be different.

EXPENSE TABLE

Fund expenses borne by the shareholders during the period, September 1, 2017 through February 28, 2018

The example is based on an investment of $1,000 invested at the beginning of the period and held for the entire period September 1, 2017 through February 28, 2018.

Actual Expenses

Hypothetical Example for Comparison Purposes

Expense Table – continued


Share Class		Annualized Expense Ratio		Beginning Account Value 9/01/17		Ending Account Value 2/28/18		Expenses Paid During Period (p) 9/01/17-2/28/18
A	Actual		1.32%		$1,000.00		$1,130.54		$6.97
A	Hypothetical (h)		1.32%		$1,000.00		$1,018.25		$6.61
B	Actual		2.07%		$1,000.00		$1,126.50		$10.91
B	Hypothetical (h)		2.07%		$1,000.00		$1,014.53		$10.34
C	Actual		2.07%		$1,000.00		$1,126.71		$10.92
C	Hypothetical (h)		2.07%		$1,000.00		$1,014.53		$10.34
I	Actual		1.07%		$1,000.00		$1,132.23		$5.66
I	Hypothetical (h)		1.07%		$1,000.00		$1,019.49		$5.36
R1	Actual		2.07%		$1,000.00		$1,126.44		$10.91
R1	Hypothetical (h)		2.07%		$1,000.00		$1,014.53		$10.34
R2	Actual		1.57%		$1,000.00		$1,129.55		$8.29
R2	Hypothetical (h)		1.57%		$1,000.00		$1,017.01		$7.85
R3	Actual		1.32%		$1,000.00		$1,130.69		$6.97
R3	Hypothetical (h)		1.32%		$1,000.00		$1,018.25		$6.61
R4	Actual		1.07%		$1,000.00		$1,133.25		$5.66
R4	Hypothetical (h)		1.07%		$1,000.00		$1,019.49		$5.36
R6	Actual		0.96%		$1,000.00		$1,132.68		$5.08
R6	Hypothetical (h)		0.96%		$1,000.00		$1,020.03		$4.81
529A	Actual		1.35%		$1,000.00		$1,130.86		$7.13
529A	Hypothetical (h)		1.35%		$1,000.00		$1,018.10		$6.76
529B	Actual		2.12%		$1,000.00		$1,126.52		$11.18
529B	Hypothetical (h)		2.12%		$1,000.00		$1,014.28		$10.59
529C	Actual		2.12%		$1,000.00		$1,126.58		$11.18
529C	Hypothetical (h)		2.12%		$1,000.00		$1,014.28		$10.59

(h)	5% class return per year before expenses.

(p)

Notes to Expense Table

Each class with a Rule 12b-1 service fee is subject to a rebate of a portion of such fee. Such rebates are included in the expense ratios above. For Class A, Class B, Class 529A, and Class 529B shares, this rebate reduced the expense ratios above by 0.01%, 0.01%, 0.02%, and 0.01%, respectively. See Note 3 in the Notes to Financial Statements for additional information.

PORTFOLIO OF INVESTMENTS

2/28/18 (unaudited)

The Portfolio of Investments is a complete list of all securities owned by your fund. It is categorized by broad-based asset classes.


Common Stocks - 97.5%
Issuer	Shares/Par		Value ($)
Aerospace - 3.7%
CACI International, Inc., “A” (a)		83,200	$	12,400,960
Curtiss-Wright Corp.		103,731		14,001,611
FLIR Systems, Inc.		216,302		10,620,428
HEICO Corp.		59,600		5,101,760

			$	42,124,759
Automotive - 2.4%
Kar Auction Services, Inc.		337,961	$	18,276,931
WABCO Holdings, Inc. (a)		66,918		9,232,676

			$	27,509,607
Biotechnology - 4.8%
ACADIA Pharmaceuticals, Inc. (a)		91,435	$	2,278,103
Aimmune Therapeutics, Inc. (a)		134,837		4,382,203
Alder Biopharmaceuticals, Inc. (a)		320,361		4,453,018
Amicus Therapeutics, Inc. (a)		461,546		6,350,873
Bio-Techne Corp.		69,067		9,761,930
Exact Sciences Corp. (a)		99,632		4,444,584
Immunomedics, Inc (a)		328,541		5,555,628
MiMedx Group, Inc. (a)(l)		329,382		2,335,318
Neurocrine Biosciences, Inc. (a)		72,348		6,108,342
Spark Therapeutics, Inc. (a)		79,710		4,551,441
Tesaro, Inc. (a)		45,666		2,522,133
VTV Therapeutics, Inc. (a)		275,016		1,553,840

			$	54,297,413
Brokerage & Asset Managers - 1.8%
Hamilton Lane, Inc.,“A”		148,846	$	5,200,679
TMX Group Ltd.		107,980		6,455,070
WisdomTree Investments, Inc.		881,037		8,466,766

			$	20,122,515
Business Services - 5.4%
CoStar Group, Inc. (a)		13,734	$	4,698,814
Global Payments, Inc.		95,906		10,874,781
WNS (Holdings) Ltd., ADR (a)		282,195		12,698,775
Yext, Inc. (a)		1,200,574		15,247,290
Zendesk, Inc. (a)		428,318		18,494,771

			$	62,014,431

Portfolio of Investments (unaudited) – continued


Issuer	Shares/Par		Value ($)
Common Stocks - continued
Chemicals - 1.3%
Ingevity Corp. (a)		194,720	$	14,586,475

Computer Software - 8.4%
8x8, Inc. (a)		659,055	$	12,027,754
Cadence Design Systems, Inc. (a)		202,985		7,869,728
MuleSoft, Inc., “A” (a)		409,314		12,639,616
Okta, Inc. (a)		115,671		4,463,744
Paylocity Holding Corp. (a)		299,302		13,998,355
RingCentral, Inc. (a)		163,907		10,268,774
SendGrid, Inc. (a)		311,585		8,138,600
Twilio, Inc., “A” (a)		459,177		15,685,486
Ultimate Software Group, Inc. (a)		45,822		10,926,714

			$	96,018,771
Computer Software - Systems - 13.4%
Box, Inc. (a)		593,213	$	14,272,705
Five9, Inc. (a)		487,520		14,801,107
ForeScout Tech, Inc. (a)		303,552		9,039,779
Interxion Holding N.V. (a)		181,852		10,238,268
Kinaxis, Inc. (a)		73,552		4,982,758
New Relic, Inc. (a)		145,958		10,476,865
NICE Systems Ltd., ADR (a)		196,954		19,023,787
Proofpoint, Inc. (a)		94,414		10,118,348
Q2 Holdings, Inc. (a)		297,322		13,543,017
Rapid7, Inc. (a)		505,384		13,347,191
RealPage, Inc (a)		185,910		9,713,798
SS&C Technologies Holdings, Inc.		283,479		14,037,880
Switch, Inc.		685,205		9,462,681

			$	153,058,184
Construction - 4.7%
Foundation Building Materials, Inc. (a)		661,147	$	9,051,102
GMS, Inc. (a)		382,805		11,851,643
Lennox International, Inc.		44,952		9,198,528
Siteone Landscape Supply, Inc. (a)		77,721		5,350,314
Summit Materials, Inc., “A” (a)		370,249		11,710,976
Trex Co., Inc. (a)		61,821		6,392,291

			$	53,554,854
Consumer Products - 0.7%
E.L.F. Beauty, Inc. (a)(l)		438,935	$	8,093,961

Portfolio of Investments (unaudited) – continued


Issuer	Shares/Par		Value ($)
Common Stocks - continued
Consumer Services - 2.8%
51job, Inc., ADR (a)		148,272	$	9,707,368
Bright Horizons Family Solutions, Inc. (a)		228,168		21,806,016

			$	31,513,384
Containers - 1.6%
Berry Global Group, Inc. (a)		346,872	$	18,869,837

Electrical Equipment - 2.8%
Gates Industrial Corp. PLC (a)		597,538	$	10,373,260
Littlefuse, Inc.		66,713		13,842,947
WESCO International, Inc. (a)		116,505		7,252,436

			$	31,468,643
Electronics - 4.7%
Brooks Automation, Inc.		352,169	$	9,406,434
CTS Corp.		206,091		5,296,539
Inphi Corp. (a)		328,101		9,104,803
MACOM Technology Solutions Holdings, Inc. (a)		184,061		3,927,862
Monolithic Power Systems, Inc.		97,391		11,400,590
Silicon Laboratories, Inc. (a)		150,465		14,068,477

			$	53,204,705
Entertainment - 0.9%
Live Nation, Inc. (a)		226,885	$	10,164,448

Food & Beverages - 0.9%
Blue Buffalo Pet Products, Inc. (a)		100,007	$	4,006,280
Flex Pharma, Inc. (a)(l)		222,918		913,964
Greencore Group PLC		2,041,064		4,978,038

			$	9,898,282
Internet - 2.6%
GrubHub, Inc. (a)		90,747	$	9,021,159
LogMeIn, Inc.		181,776		21,004,217

			$	30,025,376
Machinery & Tools - 1.1%
Gardner Denver Holdings, Inc. (a)		161,612	$	5,173,200
Ritchie Bros. Auctioneers, Inc.		248,380		8,045,028

			$	13,218,228
Medical & Health Technology & Services - 4.6%
Capital Senior Living Corp. (a)		291,554	$	3,437,422
ICON PLC (a)		143,251		16,231,771

Portfolio of Investments (unaudited) – continued


Issuer	Shares/Par		Value ($)
Common Stocks - continued
Medical & Health Technology & Services - continued
OptiNose, Inc. (a)		416,758	$	7,380,784
Syneos Health, Inc. (a)		288,757		12,098,918
Teladoc, Inc. (a)(l)		344,459		13,812,806

			$	52,961,701
Medical Equipment - 8.9%
DexCom, Inc. (a)		181,699	$	10,200,582
iRhythm Technologies, Inc. (a)		126,018		7,832,019
Merit Medical Systems, Inc. (a)		271,184		12,338,872
Nevro Corp. (a)		141,589		11,485,700
NuVasive, Inc. (a)		190,369		9,206,245
NxStage Medical, Inc. (a)		182,885		4,257,563
Obalon Therapeutics, Inc. (a)(l)		287,124		1,154,238
PerkinElmer, Inc.		188,775		14,411,083
Steris PLC		164,209		14,992,282
Tactile Systems Technology, Inc. (a)		200,558		6,490,057
West Pharmaceutical Services, Inc.		111,433		9,719,186

			$	102,087,827
Oil Services - 0.6%
Liberty Oilfield Services, Inc. (a)		378,198	$	7,030,701

Other Banks & Diversified Financials - 3.8%
Bank of the Ozarks, Inc.		244,041	$	12,175,206
Pinnacle Financial Partners, Inc.		157,308		10,154,231
Preferred Bank		108,341		6,752,895
Texas Capital Bancshares, Inc. (a)		48,176		4,345,475
Wintrust Financial Corp.		117,151		9,900,431

			$	43,328,238
Pharmaceuticals - 1.1%
Aratana Therapeutics, Inc. (a)(l)		608,472	$	2,263,516
Collegium Pharmaceutical, Inc. (a)		248,443		5,960,147
PetIQ, Inc. (a)		182,701		4,001,152

			$	12,224,815
Pollution Control - 1.4%
Clean Harbors, Inc. (a)		126,101	$	6,296,223
Evoqua Water Technologies LLC (a)		410,874		9,409,015

			$	15,705,238
Railroad & Shipping - 0.4%
StealthGas, Inc. (a)		976,797	$	4,112,315

Portfolio of Investments (unaudited) – continued


Issuer		Shares/Par		Value ($)
Common Stocks - continued
Real Estate - 2.1%
Big Yellow Group PLC, REIT			458,482	$	5,226,794
Life Storage, Inc., REIT			98,677		7,752,065
STAG Industrial, Inc., REIT			487,781		11,106,773
	��
				$	24,085,632
Restaurants - 5.0%
Dave & Buster’s, Inc. (a)			262,098	$	11,734,128
Performance Food Group Co. (a)			570,776		17,494,284
U.S. Foods Holding Corp. (a)			662,132		22,108,588
Zoe’s Kitchen, Inc. (a)			412,522		6,138,327

				$	57,475,327
Special Products & Services - 1.0%
Boyd Group Income Fund, IEU			136,736	$	11,273,900

Specialty Chemicals - 4.0%
Axalta Coating Systems Ltd. (a)			239,967	$	7,390,983
Ferro Corp. (a)			462,530		9,893,517
Ferroglobe PLC (a)			278,168		4,495,195
RPM International, Inc.			210,205		10,461,903
Univar, Inc. (a)			477,552		13,758,273

				$	45,999,871
Specialty Stores - 0.6%
Michaels Co., Inc. (a)			279,250	$	6,425,543
Total Common Stocks (Identified Cost, $880,621,475)				$	1,112,454,981

Investment Companies (h) - 3.0%
Money Market Funds - 3.0%
MFS Institutional Money Market Portfolio, 1.52% (v) (Identified Cost, $34,101,745)			34,106,791	$	34,103,380

Collateral for Securities Loaned - 1.1%
State Street Navigator Securities Lending Government Money Market Portfolio, 1.37% (j) (Identified Cost, $12,230,182)			12,230,182	$	12,230,182

Other Assets, Less Liabilities - (1.6)%					(18,555,619	)
Net Assets - 100.0%				$	1,140,232,924

(a)	Non-income producing security.

(h)

Portfolio of Investments (unaudited) – continued

(j)	The rate quoted is the annualized seven-day yield of the fund at period end.

(l)	A portion of this security is on loan.

(v)	Affiliated issuer that is available only to investment companies managed by MFS. The rate quoted for the MFS Institutional Money Market Portfolio is the annualized seven-day yield of the fund at period end.

The following abbreviations are used in this report and are defined:

ADR

American Depositary Receipt

IEU

International Equity Unit

PLC

Public Limited Company

REIT

Real Estate Investment Trust

See Notes to Financial Statements

Financial Statements

STATEMENT OF ASSETS AND LIABILITIES

At 2/28/18 (unaudited)

This statement represents your fund’s balance sheet, which details the assets and liabilities comprising the total value of the fund.


Assets
Investments in unaffiliated issuers, at value, including $12,217,575 of securities on loan (identified cost, $892,851,657)	$1,124,685,163
Investments in affiliated issuers, at value (identified cost, $34,101,745)	34,103,380
Cash	21,366
Receivables for
Investments sold	742,079
Fund shares sold	1,234,669
Interest and dividends	548,828
Other assets	4,700
Total assets	$1,161,340,185
Liabilities
Payables for
Investments purchased	$5,590,614
Fund shares reacquired	2,860,986
Collateral for securities loaned, at value	12,230,182
Payable to affiliates
Investment adviser	56,550
Shareholder servicing costs	310,364
Distribution and service fees	10,474
Program manager fee	24
Payable for independent Trustees’ compensation	2,042
Accrued expenses and other liabilities	46,025
Total liabilities	$21,107,261
Net assets	$1,140,232,924
Net assets consist of
Paid-in capital	$817,549,405
Unrealized appreciation (depreciation)	231,838,858
Accumulated net realized gain (loss)	94,717,347
Accumulated net investment loss	(3,872,686	)
Net assets	$1,140,232,924
Shares of beneficial interest outstanding	39,920,932

Statement of Assets and Liabilities (unaudited) – continued


	Net assets		Shares outstanding		Net asset value per share (a)
Class A		$409,765,444		14,691,376		$27.89
Class B		20,618,921		913,095		22.58
Class C		79,311,674		3,504,826		22.63
Class I		116,601,942		3,784,973		30.81
Class R1		4,582,226		204,442		22.41
Class R2		30,412,118		1,158,317		26.26
Class R3		42,937,323		1,541,354		27.86
Class R4		9,570,800		326,437		29.32
Class R6		417,612,965		13,450,786		31.05
Class 529A		6,772,292		251,234		26.96
Class 529B		351,553		16,151		21.77
Class 529C		1,695,666		77,941		21.76

(a)

Maximum offering price per share was equal to the net asset value per share for all share classes, except for Classes A and 529A, for which the maximum offering prices per share were $29.59 [100 / 94.25 x $27.89] and $28.60 [100 / 94.25 x $26.96], respectively. On sales of $50,000 or more, the maximum offering prices of Class A and Class 529A shares are reduced. A contingent deferred sales charge may be imposed on redemptions of Class A, Class B, Class C, Class 529B, and Class 529C shares. Redemption price per share was equal to the net asset value per share for Classes I, R1, R2, R3, R4, R6, and 529A. Net asset value per share is calculated using actual net assets and shares outstanding rather than amounts that have been rounded for presentation purposes.

See Notes to Financial Statements

Financial Statements

STATEMENT OF OPERATIONS

Six months ended 2/28/18 (unaudited)

This statement describes how much your fund earned in investment income and accrued in expenses. It also describes any gains and/or losses generated by fund operations.


Net investment income (loss)
Income
Dividends	$2,605,489
Income on securities loaned	515,528
Dividends from affiliated issuers	191,902
Foreign taxes withheld	(39,227	)
Total investment income	$3,273,692
Expenses
Management fee	$5,118,605
Distribution and service fees	1,162,594
Shareholder servicing costs	605,213
Program manager fees	3,231
Administrative services fee	91,800
Independent Trustees’ compensation	12,382
Custodian fee	33,455
Shareholder communications	47,388
Audit and tax fees	29,150
Legal fees	6,162
Miscellaneous	99,018
Total expenses	$7,208,998
Reduction of expenses by investment adviser and distributor	(64,694	)
Net expenses	$7,144,304
Net investment income (loss)	$(3,870,612	)
Realized and unrealized gain (loss)
Realized gain (loss) (identified cost basis)
Unaffiliated issuers	$140,981,833
Affiliated issuers	(3,270	)
Foreign currency	(5,385	)
Net realized gain (loss)	$140,973,178
Change in unrealized appreciation (depreciation)
Unaffiliated issuers	$7,184,725
Affiliated issuers	(708	)
Translation of assets and liabilities in foreign currencies	5,027
Net unrealized gain (loss)	$7,189,044
Net realized and unrealized gain (loss)	$148,162,222
Change in net assets from operations	$144,291,610

See Notes to Financial Statements

Financial Statements

STATEMENTS OF CHANGES IN NET ASSETS

These statements describe the increases and/or decreases in net assets resulting from operations, any distributions, and any shareholder transactions.


Change in net assets	Six months ended 2/28/18 (unaudited)			Year ended 8/31/17
From operations
Net investment income (loss)		$(3,870,612	)		$(7,026,746	)
Net realized gain (loss)		140,973,178			100,786,912
Net unrealized gain (loss)		7,189,044			71,433,498
Change in net assets from operations		$144,291,610			$165,193,664
Distributions declared to shareholders
From net realized gain		$(110,787,326	)		$(25,588,520	)
Change in net assets from fund share transactions		$(43,775,658	)		$(118,490,984	)
Total change in net assets		$(10,271,374	)		$21,114,160
Net assets
At beginning of period		1,150,504,298			1,129,390,138
At end of period (including accumulated net investment loss of $3,872,686 and $2,074, respectively)		$1,140,232,924			$1,150,504,298

See Notes to Financial Statements

Financial Statements

FINANCIAL HIGHLIGHTS

The financial highlights table is intended to help you understand the fund’s financial performance for the semiannual period and the past 5 fiscal years. Certain information reflects financial results for a single fund share. The total returns in the table represent the rate that an investor would have earned (or lost) on an investment in the fund share class (assuming reinvestment of all distributions) held for the entire period.


	Six months ended 2/28/18			Year ended
Class A	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14			8/31/13
	(unaudited)
Net asset value, beginning of period		$27.27			$24.11			$23.69			$25.49			$25.86			$20.17
Income (loss) from investment operations
Net investment income (loss) (d)		$(0.11	)		$(0.18	)(c)		$(0.11	)		$(0.20	)		$(0.22	)		$(0.14	)
Net realized and unrealized gain (loss)		3.54			3.92			0.53			0.22			2.30			5.83
Total from investment operations		$3.43			$3.74			$0.42			$0.02			$2.08			$5.69
Less distributions declared to shareholders
From net realized gain		$(2.81	)		$(0.58	)		$—			$(1.82	)		$(2.45	)		$—
Net asset value, end of period (x)		$27.89			$27.27			$24.11			$23.69			$25.49			$25.86
Total return (%) (r)(s)(t)(x)		13.05	(n)		15.83	(c)		1.77			0.47			8.01			28.21
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.33	(a)		1.35	(c)		1.36			1.36			1.33			1.35
Expenses after expense reductions (f)		1.32	(a)		1.33	(c)		1.34			1.31			1.27			1.31
Net investment income (loss)		(0.75	)(a)		(0.70	)(c)		(0.50	)		(0.81	)		(0.83	)		(0.59	)
Portfolio turnover		57	(n)		53			49			56			98			96
Net assets at end of period (000 omitted)		$409,765			$394,878			$400,997			$457,437			$620,802			$866,006

See Notes to Financial Statements

Financial Highlights – continued


	Six months ended 2/28/18			Year ended
Class B	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14			8/31/13
	(unaudited)
Net asset value, beginning of period		$22.65			$20.27			$20.07			$22.04			$22.83			$17.94
Income (loss) from investment operations
Net investment income (loss) (d)		$(0.17	)		$(0.30	)(c)		$(0.24	)		$(0.32	)		$(0.36	)		$(0.27	)
Net realized and unrealized gain (loss)		2.91			3.26			0.44			0.17			2.02			5.16
Total from investment operations		$2.74			$2.96			$0.20			$(0.15	)		$1.66			$4.89
Less distributions declared to shareholders
From net realized gain		$(2.81	)		$(0.58	)		$—			$(1.82	)		$(2.45	)		$—
Net asset value, end of period (x)		$22.58			$22.65			$20.27			$20.07			$22.04			$22.83
Total return (%) (r)(s)(t)(x)		12.65	(n)		14.97	(c)		1.00			(0.27	)		7.18			27.26
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		2.08	(a)		2.10	(c)		2.11			2.11			2.08			2.10
Expenses after expense reductions (f)		2.07	(a)		2.08	(c)		2.09			2.06			2.02			2.06
Net investment income (loss)		(1.51	)(a)		(1.45	)(c)		(1.26	)		(1.57	)		(1.58	)		(1.34	)
Portfolio turnover		57	(n)		53			49			56			98			96
Net assets at end of period (000 omitted)		$20,619			$20,143			$22,906			$27,455			$34,971			$37,952

	Six months ended 2/28/18			Year ended
Class C	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14			8/31/13
	(unaudited)
Net asset value, beginning of period		$22.70			$20.31			$20.11			$22.08			$22.86			$17.96
Income (loss) from investment operations
Net investment income (loss) (d)		$(0.17	)		$(0.31	)(c)		$(0.24	)		$(0.32	)		$(0.36	)		$(0.27	)
Net realized and unrealized gain (loss)		2.91			3.28			0.44			0.17			2.03			5.17
Total from investment operations		$2.74			$2.97			$0.20			$(0.15	)		$1.67			$4.90
Less distributions declared to shareholders
From net realized gain		$(2.81	)		$(0.58	)		$—			$(1.82	)		$(2.45	)		$—
Net asset value, end of period (x)		$22.63			$22.70			$20.31			$20.11			$22.08			$22.86
Total return (%) (r)(s)(t)(x)		12.62	(n)		14.99	(c)		0.99			(0.28	)		7.22			27.28
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		2.08	(a)		2.10	(c)		2.11			2.11			2.08			2.10
Expenses after expense reductions (f)		2.07	(a)		2.09	(c)		2.09			2.06			2.02			2.06
Net investment income (loss)		(1.51	)(a)		(1.45	)(c)		(1.27	)		(1.57	)		(1.59	)		(1.35	)
Portfolio turnover		57	(n)		53			49			56			98			96
Net assets at end of period (000 omitted)		$79,312			$76,724			$85,370			$105,686			$141,293			$136,913

See Notes to Financial Statements

Financial Highlights – continued


	Six months ended 2/28/18			Year ended
Class I	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14			8/31/13
	(unaudited)
Net asset value, beginning of period		$29.81			$26.24			$25.72			$27.44			$27.61			$21.48
Income (loss) from investment operations
Net investment income (loss) (d)		$(0.08	)		$(0.12	)(c)		$(0.07	)		$(0.14	)		$(0.17	)		$(0.09	)
Net realized and unrealized gain (loss)		3.89			4.27			0.59			0.24			2.45			6.22
Total from investment operations		$3.81			$4.15			$0.52			$0.10			$2.28			$6.13
Less distributions declared to shareholders
From net realized gain		$(2.81	)		$(0.58	)		$—			$(1.82	)		$(2.45	)		$—
Net asset value, end of period (x)		$30.81			$29.81			$26.24			$25.72			$27.44			$27.61
Total return (%) (r)(s)(t)(x)		13.22	(n)		16.12	(c)		2.02			0.74			8.25			28.54
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.08	(a)		1.10	(c)		1.12			1.11			1.08			1.10
Expenses after expense reductions (f)		1.07	(a)		1.09	(c)		1.09			1.06			1.02			1.06
Net investment income (loss)		(0.51	)(a)		(0.45	)(c)		(0.30	)		(0.55	)		(0.59	)		(0.36	)
Portfolio turnover		57	(n)		53			49			56			98			96
Net assets at end of period (000 omitted)		$116,602			$106,459			$101,635			$166,513			$483,893			$368,806

	Six months ended 2/28/18			Year ended
Class R1	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14			8/31/13
	(unaudited)
Net asset value, beginning of period		$22.50			$20.15			$19.94			$21.91			$22.71			$17.84
Income (loss) from investment operations
Net investment income (loss) (d)		$(0.17	)		$(0.30	)(c)		$(0.23	)		$(0.32	)		$(0.36	)		$(0.27	)
Net realized and unrealized gain (loss)		2.89			3.23			0.44			0.17			2.01			5.14
Total from investment operations		$2.72			$2.93			$0.21			$(0.15	)		$1.65			$4.87
Less distributions declared to shareholders
From net realized gain		$(2.81	)		$(0.58	)		$—			$(1.82	)		$(2.45	)		$—
Net asset value, end of period (x)		$22.41			$22.50			$20.15			$19.94			$21.91			$22.71
Total return (%) (r)(s)(t)(x)		12.64	(n)		14.91	(c)		1.05			(0.28	)		7.17			27.30
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		2.08	(a)		2.10	(c)		2.11			2.11			2.08			2.10
Expenses after expense reductions (f)		2.07	(a)		2.09	(c)		2.09			2.06			2.02			2.06
Net investment income (loss)		(1.51	)(a)		(1.45	)(c)		(1.26	)		(1.57	)		(1.59	)		(1.34	)
Portfolio turnover		57	(n)		53			49			56			98			96
Net assets at end of period (000 omitted)		$4,582			$4,377			$5,647			$6,573			$8,490			$8,972

See Notes to Financial Statements

Financial Highlights – continued


	Six months ended 2/28/18			Year ended
Class R2	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14			8/31/13
	(unaudited)
Net asset value, beginning of period		$25.85			$22.95			$22.60			$24.46			$24.97			$19.52
Income (loss) from investment operations
Net investment income (loss) (d)		$(0.13	)		$(0.23	)(c)		$(0.17	)		$(0.25	)		$(0.27	)		$(0.19	)
Net realized and unrealized gain (loss)		3.35			3.71			0.52			0.21			2.21			5.64
Total from investment operations		$3.22			$3.48			$0.35			$(0.04	)		$1.94			$5.45
Less distributions declared to shareholders
From net realized gain		$(2.81	)		$(0.58	)		$—			$(1.82	)		$(2.45	)		$—
Net asset value, end of period (x)		$26.26			$25.85			$22.95			$22.60			$24.46			$24.97
Total return (%) (r)(s)(t)(x)		12.96	(n)		15.50	(c)		1.55			0.23			7.72			27.92
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.58	(a)		1.60	(c)		1.62			1.61			1.58			1.60
Expenses after expense reductions (f)		1.57	(a)		1.59	(c)		1.59			1.56			1.52			1.56
Net investment income (loss)		(1.01	)(a)		(0.95	)(c)		(0.82	)		(1.07	)		(1.09	)		(0.85	)
Portfolio turnover		57	(n)		53			49			56			98			96
Net assets at end of period (000 omitted)		$30,412			$29,130			$35,890			$57,077			$66,923			$60,501

	Six months ended 2/28/18			Year ended
Class R3	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14			8/31/13
	(unaudited)
Net asset value, beginning of period		$27.24			$24.09			$23.67			$25.47			$25.84			$20.15
Income (loss) from investment operations
Net investment income (loss) (d)		$(0.11	)		$(0.17	)(c)		$(0.12	)		$(0.20	)		$(0.22	)		$(0.14	)
Net realized and unrealized gain (loss)		3.54			3.90			0.54			0.22			2.30			5.83
Total from investment operations		$3.43			$3.73			$0.42			$0.02			$2.08			$5.69
Less distributions declared to shareholders
From net realized gain		$(2.81	)		$(0.58	)		$—			$(1.82	)		$(2.45	)		$—
Net asset value, end of period (x)		$27.86			$27.24			$24.09			$23.67			$25.47			$25.84
Total return (%) (r)(s)(t)(x)		13.07	(n)		15.81	(c)		1.77			0.47			8.02			28.24
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.33	(a)		1.35	(c)		1.37			1.36			1.33			1.35
Expenses after expense reductions (f)		1.32	(a)		1.34	(c)		1.34			1.31			1.27			1.31
Net investment income (loss)		(0.76	)(a)		(0.70	)(c)		(0.55	)		(0.82	)		(0.84	)		(0.60	)
Portfolio turnover		57	(n)		53			49			56			98			96
Net assets at end of period (000 omitted)		$42,937			$42,346			$57,593			$89,659			$150,359			$110,562

See Notes to Financial Statements

Financial Highlights – continued


	Six months ended 2/28/18			Year ended
Class R4	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14			8/31/13
	(unaudited)
Net asset value, beginning of period		$28.48			$25.09			$24.60			$26.33			$26.57			$20.67
Income (loss) from investment operations
Net investment income (loss) (d)		$(0.07	)		$(0.12	)(c)		$(0.07	)		$(0.14	)		$(0.16	)		$(0.08	)
Net realized and unrealized gain (loss)		3.72			4.09			0.56			0.23			2.37			5.98
Total from investment operations		$3.65			$3.97			$0.49			$0.09			$2.21			$5.90
Less distributions declared to shareholders
From net realized gain		$(2.81	)		$(0.58	)		$—			$(1.82	)		$(2.45	)		$—
Net asset value, end of period (x)		$29.32			$28.48			$25.09			$24.60			$26.33			$26.57
Total return (%) (r)(s)(t)(x)		13.29	(n)		16.14	(c)		1.99			0.73			8.31			28.54
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.08	(a)		1.10	(c)		1.12			1.11			1.08			1.10
Expenses after expense reductions (f)		1.07	(a)		1.09	(c)		1.09			1.06			1.02			1.06
Net investment income (loss)		(0.49	)(a)		(0.45	)(c)		(0.32	)		(0.57	)		(0.59	)		(0.35	)
Portfolio turnover		57	(n)		53			49			56			98			96
Net assets at end of period (000 omitted)		$9,571			$83,186			$91,974			$142,857			$229,964			$197,884

	Six months ended 2/28/18			Year ended
Class R6	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14			8/31/13
	(unaudited)
Net asset value, beginning of period		$30.01			$26.38			$25.83			$27.52			$27.64			$21.48
Income (loss) from investment operations
Net investment income (loss) (d)		$(0.06	)		$(0.09	)(c)		$(0.03	)		$(0.12	)		$(0.13	)		$(0.06	)
Net realized and unrealized gain (loss)		3.91			4.30			0.58			0.25			2.46			6.22
Total from investment operations		$3.85			$4.21			$0.55			$0.13			$2.33			$6.16
Less distributions declared to shareholders
From net realized gain		$(2.81	)		$(0.58	)		$—			$(1.82	)		$(2.45	)		$—
Net asset value, end of period (x)		$31.05			$30.01			$26.38			$25.83			$27.52			$27.64
Total return (%) (r)(s)(t)(x)		13.27	(n)		16.26	(c)		2.13			0.85			8.43			28.68
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		0.97	(a)		0.98	(c)		0.99			0.98			0.97			0.99
Expenses after expense reductions (f)		0.96	(a)		0.97	(c)		0.97			0.93			0.91			0.96
Net investment income (loss)		(0.40	)(a)		(0.34	)(c)		(0.11	)		(0.44	)		(0.48	)		(0.24	)
Portfolio turnover		57	(n)		53			49			56			98			96
Net assets at end of period (000 omitted)		$417,613			$385,440			$320,645			$313,080			$319,139			$244,655

See Notes to Financial Statements

Financial Highlights – continued


	Six months ended 2/28/18			Year ended
Class 529A	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14			8/31/13
	(unaudited)
Net asset value, beginning of period		$26.45			$23.41			$23.01			$24.82			$25.25			$19.70
Income (loss) from investment operations
Net investment income (loss) (d)		$(0.11	)		$(0.18	)(c)		$(0.11	)		$(0.20	)		$(0.22	)		$(0.14	)
Net realized and unrealized gain (loss)		3.43			3.80			0.51			0.21			2.24			5.69
Total from investment operations		$3.32			$3.62			$0.40			$0.01			$2.02			$5.55
Less distributions declared to shareholders
From net realized gain		$(2.81	)		$(0.58	)		$—			$(1.82	)		$(2.45	)		$—
Net asset value, end of period (x)		$26.96			$26.45			$23.41			$23.01			$24.82			$25.25
Total return (%) (r)(s)(t)(x)		13.04	(n)		15.80	(c)		1.74			0.44			7.97			28.17
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.41	(a)		1.45	(c)		1.46			1.46			1.43			1.45
Expenses after expense reductions (f)		1.35	(a)		1.37	(c)		1.37			1.34			1.30			1.34
Net investment income (loss)		(0.78	)(a)		(0.73	)(c)		(0.50	)		(0.85	)		(0.86	)		(0.62	)
Portfolio turnover		57	(n)		53			49			56			98			96
Net assets at end of period (000 omitted)		$6,772			$5,902			$5,075			$5,149			$5,150			$4,519

	Six months ended 2/28/18			Year ended
Class 529B	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14			8/31/13
	(unaudited)
Net asset value, beginning of period		$21.93			$19.66			$19.47			$21.44			$22.27			$17.51
Income (loss) from investment operations
Net investment income (loss) (d)		$(0.17	)		$(0.30	)(c)		$(0.23	)		$(0.32	)		$(0.36	)		$(0.28	)
Net realized and unrealized gain (loss)		2.82			3.15			0.42			0.17			1.98			5.04
Total from investment operations		$2.65			$2.85			$0.19			$(0.15	)		$1.62			$4.76
Less distributions declared to shareholders
From net realized gain		$(2.81	)		$(0.58	)		$—			$(1.82	)		$(2.45	)		$—
Net asset value, end of period (x)		$21.77			$21.93			$19.66			$19.47			$21.44			$22.27
Total return (%) (r)(s)(t)(x)		12.65	(n)		14.87	(c)		0.98			(0.28	)		7.18			27.18
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		2.16	(a)		2.20	(c)		2.21			2.21			2.18			2.20
Expenses after expense reductions (f)		2.12	(a)		2.13	(c)		2.12			2.09			2.06			2.10
Net investment income (loss)		(1.55	)(a)		(1.49	)(c)		(1.28	)		(1.60	)		(1.62	)		(1.39	)
Portfolio turnover		57	(n)		53			49			56			98			96
Net assets at end of period (000 omitted)		$352			$325			$306			$341			$348			$300

See Notes to Financial Statements

Financial Highlights – continued


	Six months ended 2/28/18			Year ended
Class 529C	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14			8/31/13
	(unaudited)
Net asset value, beginning of period		$21.93			$19.65			$19.46			$21.44			$22.28			$17.52
Income (loss) from investment operations
Net investment income (loss) (d)		$(0.17	)		$(0.31	)(c)		$(0.23	)		$(0.33	)		$(0.36	)		$(0.28	)
Net realized and unrealized gain (loss)		2.81			3.17			0.42			0.17			1.97			5.04
Total from investment operations		$2.64			$2.86			$0.19			$(0.16	)		$1.61			$4.76
Less distributions declared to shareholders
From net realized gain		$(2.81	)		$(0.58	)		$—			$(1.82	)		$(2.45	)		$—
Net asset value, end of period (x)		$21.76			$21.93			$19.65			$19.46			$21.44			$22.28
Total return (%) (r)(s)(t)(x)		12.61	(n)		14.93	(c)		0.98			(0.34	)		7.13			27.17
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		2.16	(a)		2.20	(c)		2.21			2.21			2.18			2.20
Expenses after expense reductions (f)		2.12	(a)		2.13	(c)		2.14			2.11			2.07			2.11
Net investment income (loss)		(1.56	)(a)		(1.50	)(c)		(1.28	)		(1.62	)		(1.63	)		(1.39	)
Portfolio turnover		57	(n)		53			49			56			98			96
Net assets at end of period (000 omitted)		$1,696			$1,595			$1,351			$1,383			$1,223			$1,454

(a)	Annualized.

(c)	Amount reflects a one-time reimbursement of expenses by the custodian (or former custodian) without which net investment income and performance would be lower and expenses would be higher.

(d)	Per share data is based on average shares outstanding.

(f)	Ratios do not reflect reductions from fees paid indirectly, if applicable.

(n)	Not annualized.

(r)	Certain expenses have been reduced without which performance would have been lower.

(s)	From time to time the fund may receive proceeds from litigation settlements, without which performance would be lower.

(t)	Total returns do not include any applicable sales charges.

(x)	The net asset values and total returns have been calculated on net assets which include adjustments made in accordance with U.S. generally accepted accounting principles required at period end for financial reporting purposes.

See Notes to Financial Statements

NOTES TO FINANCIAL STATEMENTS

(unaudited)

(1) Business and Organization

MFS New Discovery Fund (the fund) is a diversified series of MFS Series Trust I (the trust). The trust is organized as a Massachusetts business trust and is registered under the Investment Company Act of 1940, as amended, as an open-end management investment company.

(2) Significant Accounting Policies

General – The preparation of financial statements in conformity with U.S. generally accepted accounting principles requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of increases and decreases in net assets from operations during the reporting period. Actual results could differ from those estimates. In the preparation of these financial statements, management has evaluated subsequent events occurring after the date of the fund’s Statement of Assets and Liabilities through the date that the financial statements were issued. The fund will generally focus on securities of small size companies which may be more volatile than those of larger companies.

Notes to Financial Statements (unaudited) – continued

values of foreign securities and other assets and liabilities expressed in foreign currencies are converted to U.S. dollars using the mean of bid and asked prices for rates provided by a third-party pricing service.

Accordingly, the fund’s foreign equity securities may often be valued at fair value. The adviser generally relies on third-party pricing services or other information (such as the correlation with price movements of similar securities in the same or other markets; the type, cost and investment characteristics of the security; the business and financial condition of the issuer; and trading and other market data) to assist in determining whether to fair value and at what value to fair value an investment. The value of an investment for purposes of calculating the fund’s net asset value can differ depending on the source and method used to determine value. When fair valuation is used, the value of an investment used to determine the fund’s net asset value may differ from quoted or published prices for the same investment. There can be no assurance that the fund could obtain the fair value assigned to an investment if it were to sell the investment at the same time at which the fund determines its net asset value per share.

Notes to Financial Statements (unaudited) – continued

the fair value of investments. The following is a summary of the levels used as of February 28, 2018 in valuing the fund’s assets or liabilities:


	Level 1		Level 2		Level 3		Total
Financial Instruments
Equity Securities:
United States		$1,015,712,879		$—		$—		$1,015,712,879
Canada		30,756,757		—		—		30,756,757
Israel		19,023,787		—		—		19,023,787
India		12,698,775		—		—		12,698,775
Netherlands		10,238,268		—		—		10,238,268
United Kingdom		—		10,204,832		—		10,204,832
China		9,707,368		—		—		9,707,368
Greece		4,112,315		—		—		4,112,315
Mutual Funds		46,333,562		—		—		46,333,562
Total		$1,148,583,711		$10,204,832		$—		$1,158,788,543

For further information regarding security characteristics, see the Portfolio of Investments.

Of the level 2 investments presented above, equity investments amounting to $10,204,832 would have been considered level 1 investments at the beginning of the period. The primary reason for changes in the classifications between levels 1 and 2 occurs when foreign equity securities are fair valued using other observable market-based inputs in place of the closing exchange price due to events occurring after the close of the exchange or market on which the investment is principally traded. The fund’s foreign equity securities may often be valued using other observable market-based inputs. The fund’s policy is to recognize transfers between the levels as of the end of the period.

Notes to Financial Statements (unaudited) – continued

collateralized by cash, the cash collateral is invested in a money market fund. The market value of the loaned securities is determined at the close of business of the fund and any additional required collateral is delivered to the fund on the next business day. State Street provides the fund with indemnification against Borrower default. In the event of Borrower default, State Street will, for the benefit of the fund, either purchase securities identical to those loaned or, when such purchase is commercially impracticable, pay the fund the market value of the loaned securities. In return, State Street assumes the fund’s rights to the related collateral. If the collateral value is less than the cost to purchase identical securities, State Street is responsible for the shortfall, but only to the extent that such shortfall is not due to a decline in collateral value resulting from collateral reinvestment for which the fund bears the risk of loss. At period end, the fund had investment securities on loan, all of which were classified as equity securities in the fund’s Portfolio of Investments, with a fair value of $12,217,575. The fair value of the fund’s investment securities on loan and a related liability of $12,230,182 for cash collateral received on securities loaned are both presented gross in the Statement of Assets and Liabilities. The collateral on securities loaned exceeded the value of securities on loan at period end. The liability for cash collateral for securities loaned is carried at fair value, which is categorized as level 2 within the fair value hierarchy. A portion of the income generated upon investment of the collateral is remitted to the Borrowers, and the remainder is allocated between the fund and the lending agent. On loans collateralized by U.S. Treasury and/or federal agency obligations, a fee is received from the Borrower, and is allocated between the fund and the lending agent. Income from securities lending is separately reported in the Statement of Operations. The dividend and interest income earned on the securities loaned is accounted for in the same manner as other dividend and interest income.

Tax Matters and Distributions – The fund intends to qualify as a regulated investment company, as defined under Subchapter M of the Internal Revenue Code,

Notes to Financial Statements (unaudited) – continued

and to distribute all of its taxable income, including realized capital gains. As a result, no provision for federal income tax is required. The fund’s federal tax returns, when filed, will remain subject to examination by the Internal Revenue Service for a three year period. Management has analyzed the fund’s tax positions taken on federal and state tax returns for all open tax years and does not believe that there are any uncertain tax positions that require recognition of a tax liability. Foreign taxes, if any, have been accrued by the fund in the accompanying financial statements in accordance with the applicable foreign tax law. Foreign income taxes may be withheld by certain countries in which the fund invests. Additionally, capital gains realized by the fund on securities issued in or by certain foreign countries may be subject to capital gains tax imposed by those countries.

Book/tax differences primarily relate to wash sale loss deferrals and treating a portion of the proceeds from redemptions as a distribution for tax purposes.


	Year ended 8/31/17
Long-term capital gains		$25,588,520

The federal tax cost and the tax basis components of distributable earnings were as follows:


As of 2/28/18
Cost of investments	$928,296,425
Gross appreciation	285,785,276
Gross depreciation	(55,293,158	)
Net unrealized appreciation (depreciation)	$230,492,118

As of 8/31/17
Undistributed ordinary income	24,502,943
Undistributed long-term capital gain	41,371,575
Other temporary differences	(3,384	)
Net unrealized appreciation (depreciation)	223,308,101

The aggregate cost above includes prior fiscal year end tax adjustments, if applicable.

Notes to Financial Statements (unaudited) – continued

Multiple Classes of Shares of Beneficial Interest – The fund offers multiple classes of shares, which differ in their respective distribution, service, and program manager fees. The fund’s income, realized and unrealized gain (loss), and common expenses are allocated to shareholders based on the daily net assets of each class. Dividends are declared separately for each class. Differences in per share dividend rates are generally due to differences in separate class expenses. Class B and Class 529B shares will convert to Class A and Class 529A shares, respectively, approximately eight years after purchase. Effective April 23, 2018, Class C and Class 529C shares will convert to Class A and Class 529A shares, respectively, approximately ten years after purchase. The fund’s distributions declared to shareholders as reported in the Statements of Changes in Net Assets are presented by class as follows:


	From net realized gain on investments
	Six months ended 2/28/18		Year ended 8/31/17
Class A		$37,646,733		$9,172,597
Class B		2,381,568		584,795
Class C		9,115,914		2,281,782
Class I		10,159,237		2,526,174
Class R1		533,248		140,626
Class R2		3,004,285		824,816
Class R3		4,128,606		1,269,935
Class R4		7,995,727		1,800,361
Class R6		34,950,101		6,811,530
Class 529A		634,438		128,020
Class 529B		39,739		8,528
Class 529C		197,730		39,356
Total		$110,787,326		$25,588,520

(3) Transactions with Affiliates


Up to $1 billion	0.90	%
In excess of $1 billion and up to $2.5 billion	0.80	%
In excess of $2.5 billion and up to $5 billion	0.75	%
In excess of $5 billion	0.70	%

MFS has agreed in writing to reduce its management fee by a specified amount if certain MFS mutual fund assets exceed thresholds agreed to by MFS and the fund’s Board of Trustees. For the six months ended February 28, 2018, this management fee reduction amounted to $49,657, which is included in the reduction of total expenses in the Statement of Operations. The management fee incurred for the six months ended February 28, 2018 was equivalent to an annual effective rate of 0.88% of the fund’s average daily net assets.

Notes to Financial Statements (unaudited) – continued

Distributor – MFS Fund Distributors, Inc. (MFD), a wholly-owned subsidiary of MFS, as distributor, received $57,095 and $1,972 for the six months ended February 28, 2018, as its portion of the initial sales charge on sales of Class A and Class 529A shares of the fund, respectively.

The Board of Trustees has adopted a distribution plan for certain share classes pursuant to Rule 12b-1 of the Investment Company Act of 1940.

Distribution Plan Fee Table:


	Distribution Fee Rate (d)		Service Fee Rate (d)		Total Distribution Plan (d)		Annual Effective Rate (e)		Distribution and Service Fee
Class A		—		0.25%		0.25%		0.24%		$498,541
Class B		0.75%		0.25%		1.00%		0.99%		102,684
Class C		0.75%		0.25%		1.00%		1.00%		392,905
Class R1		0.75%		0.25%		1.00%		1.00%		22,796
Class R2		0.25%		0.25%		0.50%		0.50%		74,274
Class R3		—		0.25%		0.25%		0.25%		53,383
Class 529A		—		0.25%		0.25%		0.23%		7,972
Class 529B		0.75%		0.25%		1.00%		0.99%		1,700
Class 529C		0.75%		0.25%		1.00%		1.00%		8,339
Total Distribution and Service Fees										$1,162,594

(d)

(e)

The annual effective rates represent actual fees incurred under the distribution plan for the six months ended February 28, 2018 based on each class’s average daily net assets. MFD has voluntarily agreed to rebate a portion of each class’s 0.25% service fee attributable to accounts for which MFD retains the 0.25% service fee except for accounts attributable to MFS or its affiliates’ seed money. For the six months ended February 28, 2018, this rebate amounted to $12,411, $431, $158, $3, $83, $776, $14, and $26 for Class A, Class B, Class C, Class R1, Class R2, Class 529A, Class 529B, and Class 529C, respectively, and is included in the reduction of total expenses in the Statement of Operations.

Certain Class A shares are subject to a contingent deferred sales charge (CDSC) in the event of a shareholder redemption within 18 months of purchase. Class C and Class 529C shares are subject to a CDSC in the event of a shareholder redemption within 12 months of purchase. Class B and Class 529B shares are subject to a CDSC in the event of a shareholder redemption within six years of purchase. All contingent

Notes to Financial Statements (unaudited) – continued

deferred sales charges are paid to MFD and during the six months ended February 28, 2018, were as follows:


	Amount
Class A		$5,737
Class B		24,840
Class C		3,561
Class 529B		—
Class 529C		33

The fund has entered into and may from time to time enter into contracts with program managers and other parties which administer the tuition programs through which an investment in the fund’s 529 share classes is made. For the period from September 1, 2017 through December 10, 2017, the fund had entered into an agreement with MFD pursuant to which MFD received an annual fee of up to 0.10% of the average daily net assets attributable to each 529 share class. MFD had agreed to waive a portion of this fee in an amount equal to 0.05% of the average daily net assets for each 529 share class. This waiver agreement terminated on December 10, 2017. For the period from September 1, 2017 through December 10, 2017, this waiver amounted to $1,135 and is included in the reduction of total expenses in the Statement of Operations. Effective December 11, 2017, the fund has entered into an agreement with MFD pursuant to which MFD receives an annual fee of up to 0.05% of the average daily net assets attributable to each 529 share class. The program manager fee incurred for the six months ended February 28, 2018 was equivalent to an annual effective rate of 0.05% of the average daily net assets attributable to each 529 share class. The services provided by MFD, or a third party with which MFD contracts, include recordkeeping and tax reporting and account services, as well as services designed to maintain the program’s compliance with the Internal Revenue Code and other regulatory requirements. Program manager fees and waivers for the six months ended February 28, 2018, were as follows:


	Fee		Waiver
Class 529A	$	2,453	$	859
Class 529B		132		47
Class 529C		646		229
Total Program Manager Fees and Waivers	$	3,231	$	1,135

Shareholder Servicing Agent – MFS Service Center, Inc. (MFSC), a wholly-owned subsidiary of MFS, receives a fee from the fund for its services as shareholder servicing agent calculated as a percentage of the average daily net assets of the fund as determined periodically under the supervision of the fund’s Board of Trustees. For the six months ended February 28, 2018, the fee was $106,354, which equated to 0.0184% annually of the fund’s average daily net assets. MFSC also receives payment from the fund for out-of-pocket expenses, sub-accounting and other shareholder servicing costs which may be paid to affiliated and unaffiliated service providers. Class R6 shares do not incur sub-accounting fees. For the six months ended February 28, 2018, these out-of-pocket expenses, sub-accounting and other shareholder servicing costs amounted to $498,859.

Notes to Financial Statements (unaudited) – continued

Prior to December 31, 2001, the fund had an unfunded defined benefit plan (“DB plan”) for independent Trustees. As of December 31, 2001, the Board took action to terminate the DB plan with respect to then-current and any future independent Trustees, such that the DB plan covers only certain of those former independent Trustees who retired on or before December 31, 2001. The DB plan resulted in a pension expense of $329 and is included in “Independent Trustees’ compensation” in the Statement of Operations for the six months ended February 28, 2018. The liability for deferred retirement benefits payable to certain independent Trustees under the DB plan amounted to $1,850 at February 28, 2018, and is included in “Payable for independent Trustees’ compensation” in the Statement of Assets and Liabilities.

Other – This fund and certain other funds managed by MFS (the funds) have entered into a service agreement (the ISO Agreement) which provides for payment of fees solely by the funds to Tarantino LLC in return for the provision of services of an Independent Senior Officer (ISO) for the funds. Frank L. Tarantino serves as the ISO and is an officer of the funds and the sole member of Tarantino LLC. The funds can terminate the ISO Agreement with Tarantino LLC at any time under the terms of the ISO Agreement. For the six months ended February 28, 2018, the fee paid by the fund under this agreement was $964 and is included in “Miscellaneous” expense in the Statement of Operations. MFS has agreed to bear all expenses associated with office space, other administrative support, and supplies provided to the ISO.

On September 20, 2017, MFS purchased 206 shares of Class I for an aggregate amount of $6,234.

Notes to Financial Statements (unaudited) – continued

(4) Portfolio Securities

For the six months ended February 28, 2018, purchases and sales of investments, other than short-term obligations, aggregated $317,536,037 and $480,522,673, respectively.

(5) Shares of Beneficial Interest

The fund’s Declaration of Trust permits the Trustees to issue an unlimited number of full and fractional shares of beneficial interest. Transactions in fund shares were as follows:


	Six months ended 2/28/18				Year ended 8/31/17
	Shares		Amount		Shares		Amount
Shares sold
Class A		1,136,856		$31,866,684		2,341,848		$59,001,136
Class B		42,342		975,687		102,320		2,162,726
Class C		166,841		3,829,140		356,395		7,440,681
Class I		602,282		18,507,812		3,690,354		100,156,404
Class R1		13,785		316,826		34,848		720,340
Class R2		136,527		3,622,314		206,742		4,917,124
Class R3		136,538		3,846,709		479,936		12,115,693
Class R4		202,871		5,946,059		812,147		21,286,173
Class R6		1,147,120		35,542,338		2,895,945		83,215,903
Class 529A		20,901		567,626		35,478		853,424
Class 529B		992		21,815		1,504		30,113
Class 529C		2,089		46,643		8,513		172,895
		3,609,144		$105,089,653		10,966,030		$292,072,612

Shares issued to shareholders in reinvestment of distributions
Class A		1,371,460		$36,549,397		349,553		$8,459,180
Class B		104,219		2,252,175		26,112		527,716
Class C		375,674		8,137,106		93,965		1,902,799
Class I		300,810		8,849,833		77,460		2,044,932
Class R1		24,860		533,248		7,003		140,626
Class R2		106,349		2,669,351		32,149		738,792
Class R3		155,094		4,128,606		52,542		1,269,935
Class R4		285,766		7,995,727		71,379		1,800,181
Class R6		1,114,183		33,035,531		240,953		6,399,723
Class 529A		24,629		634,438		5,455		128,020
Class 529B		1,907		39,739		436		8,528
Class 529C		9,493		197,730		2,011		39,356
		3,874,444		$105,022,881		959,018		$23,459,788

Notes to Financial Statements (unaudited) – continued


	Six months ended 2/28/18						Year ended 8/31/17
	Shares			Amount			Shares			Amount
Shares reacquired
Class A		(2,297,349	)		$(64,771,541	)		(4,841,795	)		$(120,972,086	)
Class B		(122,670	)		(2,823,983	)		(369,005	)		(7,673,676	)
Class C		(418,272	)		(9,630,060	)		(1,272,779	)		(26,705,841	)
Class I		(689,014	)		(21,307,278	)		(4,069,947	)		(114,653,455	)
Class R1		(28,690	)		(661,584	)		(127,668	)		(2,645,579	)
Class R2		(211,284	)		(5,620,197	)		(676,252	)		(16,145,795	)
Class R3		(304,876	)		(8,545,543	)		(1,368,848	)		(34,380,875	)
Class R4		(3,083,529	)		(88,443,943	)		(1,627,560	)		(42,350,702	)
Class R6		(1,654,526	)		(51,429,568	)		(2,446,162	)		(67,477,778	)
Class 529A		(17,471	)		(474,771	)		(34,529	)		(833,352	)
Class 529B		(1,578	)		(36,550	)		(2,691	)		(53,331	)
Class 529C		(6,411	)		(143,174	)		(6,491	)		(130,914	)
		(8,835,670	)		$(253,888,192	)		(16,843,727	)		$(434,023,384	)

Net change
Class A		210,967			$3,644,540			(2,150,394	)		$(53,511,770	)
Class B		23,891			403,879			(240,573	)		(4,983,234	)
Class C		124,243			2,336,186			(822,419	)		(17,362,361	)
Class I		214,078			6,050,367			(302,133	)		(12,452,119	)
Class R1		9,955			188,490			(85,817	)		(1,784,613	)
Class R2		31,592			671,468			(437,361	)		(10,489,879	)
Class R3		(13,244	)		(570,228	)		(836,370	)		(20,995,247	)
Class R4		(2,594,892	)		(74,502,157	)		(744,034	)		(19,264,348	)
Class R6		606,777			17,148,301			690,736			22,137,848
Class 529A		28,059			727,293			6,404			148,092
Class 529B		1,321			25,004			(751	)		(14,690	)
Class 529C		5,171			101,199			4,033			81,337
		(1,352,082	)		$(43,775,658	)		(4,918,679	)		$(118,490,984	)

Class T shares were not publicly available for sale during the period. Please see the fund’s prospectus for details.

The fund is one of several mutual funds in which certain MFS funds may invest. The MFS funds do not invest in the underlying funds for the purpose of exercising management or control. At the end of the period, the MFS Growth Allocation Fund, the MFS Moderate Allocation Fund, the MFS Aggressive Growth Allocation Fund, and the MFS Conservative Allocation Fund were the owners of record of approximately 9%, 8%, 4%, and 3%, respectively, of the value of outstanding voting shares of the fund. In addition, the MFS Lifetime Income Fund, the MFS Lifetime 2020 Fund, the MFS Lifetime 2025 Fund, the MFS Lifetime 2030 Fund, the MFS Lifetime 2035 Fund, the MFS Lifetime 2040 Fund, the MFS Lifetime 2045 Fund, the MFS Lifetime 2050 Fund, the MFS Lifetime 2055 Fund, and the MFS Lifetime 2060 Fund were each the owners of record of less than 1% of the value of outstanding voting shares of the fund.

Notes to Financial Statements (unaudited) – continued

(6) Line of Credit

The fund and certain other funds managed by MFS participate in a $1.25 billion unsecured committed line of credit, subject to a $1 billion sublimit, provided by a syndication of banks under a credit agreement. Borrowings may be made for temporary financing needs. Interest is charged to each fund, based on its borrowings, generally at a rate equal to the higher of the Overnight Federal Reserve funds rate or daily one month LIBOR plus an agreed upon spread. A commitment fee, based on the average daily, unused portion of the committed line of credit, is allocated among the participating funds at the end of each calendar quarter. In addition, the fund and other funds managed by MFS have established unsecured uncommitted borrowing arrangements with certain banks for temporary financing needs. Interest is charged to each fund, based on its borrowings, at a rate equal to the Overnight Federal Reserve funds rate plus an agreed upon spread. For the six months ended February 28, 2018, the fund’s commitment fee and interest expense were $3,628 and $0, respectively, and are included in “Miscellaneous” expense in the Statement of Operations.

(7) Investments in Affiliated Issuers


Affiliated Issuers				Beginning Shares/Par Amount			Acquisitions Shares/Par Amount		Dispositions Shares/Par Amount			Ending Shares/Par Amount
MFS Institutional Money Market Portfolio					23,454,525			246,017,402		(235,365,136	)		34,106,791

Affiliated Issuers	Realized Gain (Loss)			Change in Unrealized Appreciation (Depreciation)			Capital Gain Distributions		Dividend Income			Ending Value
MFS Institutional Money Market Portfolio		$(3,270	)		$(708	)		$—		$191,902			$34,103,380

(8) Subsequent Event

The Board of Trustees of the fund has approved the termination of Class 529A, Class 529B, and Class 529C shares of the fund on or before April 27, 2018.

PROXY VOTING POLICIES AND INFORMATION

QUARTERLY PORTFOLIO DISCLOSURE

Public Reference Room

Securities and Exchange Commission

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Washington, D.C. 20549

FURTHER INFORMATION

INFORMATION ABOUT FUND CONTRACTS AND LEGAL CLAIMS

PROVISION OF FINANCIAL REPORTS AND SUMMARY PROSPECTUSES

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CONTACT

WEB SITE

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MAILING ADDRESS

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Semiannual Report

February 28, 2018

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MFS® Research International Fund

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RIF-SEM

MFS® Research International Fund

CONTENTS


Letter from the Executive Chairman			1
Portfolio composition			2
Expense table			4
Portfolio of investments			6
Statement of assets and liabilities			12
Statement of operations			14
Statements of changes in net assets			15
Financial highlights			16
Notes to financial statements			28
Proxy voting policies and information			40
Quarterly portfolio disclosure			40
Further information			40
Information about fund contracts and legal claims			41
Provision of financial reports and summary prospectuses			41
Contact information back cover

The report is prepared for the general information of shareholders.

It is authorized for distribution to prospective investors only when preceded or accompanied by a current prospectus.

NOT FDIC INSURED • MAY LOSE VALUE • NO BANK GUARANTEE

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LETTER FROM THE EXECUTIVE CHAIRMAN

Dear Shareholders:

Rising bond yields have led to a measurable uptick in market volatility — a departure from the low-volatility environment that prevailed for much of 2017. In spite of this,

U.S. protectionism is also a growing concern, as investors fear that trade friction could disrupt the synchronized uptick in global growth.

Respectfully,

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Robert J. Manning

Executive Chairman

MFS Investment Management

April 13, 2018

The opinions expressed in this letter are subject to change and may not be relied upon for investment advice. No forecasts can be guaranteed.

PORTFOLIO COMPOSITION

Portfolio structure

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Top ten holdings
Nestle S.A.			3.0%
Roche Holding AG			2.3%
Bayer AG			2.3%
Schneider Electric S.A.			2.0%
UBS AG			2.0%
AIA Group Ltd.			1.9%
BNP Paribas			1.8%
Linde AG			1.8%
Novo Nordisk A.S., “B”			1.7%
Akzo Nobel N.V.			1.7%

Global equity sectors
Financial Services			25.1%
Capital Goods			24.5%
Technology			10.0%
Health Care			9.4%
Consumer Staples			8.9%
Consumer Cyclicals			8.7%
Energy			8.1%
Telecommunications/Cable Television			4.1%


Issuer country weightings (x)
Japan			18.3%
Switzerland			13.0%
United Kingdom			11.2%
France			8.7%
Germany			8.7%
United States			6.6%
Australia			3.8%
Hong Kong			3.6%
Spain			3.0%
Other Countries			23.1%

Currency exposure weightings (y)
Euro			29.8%
Japanese Yen			18.3%
Swiss Franc			13.0%
British Pound Sterling			11.7%
United States Dollar			7.6%
Hong Kong Dollar			4.3%
Australian Dollar			3.8%
Danish Krone			2.5%
Canadian Dollar			1.8%
Other Currencies			7.2%

(x)	Represents the portfolio’s exposure to issuer countries as a percentage of a portfolio’s net assets. For purposes of this presentation, United States includes Cash & Cash Equivalents.

(y)	Represents the portfolio’s exposure to a particular currency as a percentage of a portfolio’s net assets. For purposes of this presentation, United States Dollar includes Cash & Cash Equivalents.

Portfolio Composition – continued

Percentages are based on net assets as of February 28, 2018.

The portfolio is actively managed and current holdings may be different.

EXPENSE TABLE

Fund expenses borne by the shareholders during the period, September 1, 2017 through February 28, 2018

The example is based on an investment of $1,000 invested at the beginning of the period and held for the entire period September 1, 2017 through February 28, 2018.

Actual Expenses

Hypothetical Example for Comparison Purposes

Expense Table – continued


Share Class		Annualized Expense Ratio		Beginning Account Value 9/01/17		Ending Account Value 2/28/18		Expenses Paid During Period (p) 9/01/17-2/28/18
A	Actual		1.08%		$1,000.00		$1,075.14		$5.56
A	Hypothetical (h)		1.08%		$1,000.00		$1,019.44		$5.41
B	Actual		1.83%		$1,000.00		$1,071.01		$9.40
B	Hypothetical (h)		1.83%		$1,000.00		$1,015.72		$9.15
C	Actual		1.83%		$1,000.00		$1,070.86		$9.40
C	Hypothetical (h)		1.83%		$1,000.00		$1,015.72		$9.15
I	Actual		0.83%		$1,000.00		$1,075.90		$4.27
I	Hypothetical (h)		0.83%		$1,000.00		$1,020.68		$4.16
R1	Actual		1.83%		$1,000.00		$1,070.64		$9.40
R1	Hypothetical (h)		1.83%		$1,000.00		$1,015.72		$9.15
R2	Actual		1.33%		$1,000.00		$1,072.99		$6.84
R2	Hypothetical (h)		1.33%		$1,000.00		$1,018.20		$6.66
R3	Actual		1.08%		$1,000.00		$1,074.80		$5.56
R3	Hypothetical (h)		1.08%		$1,000.00		$1,019.44		$5.41
R4	Actual		0.83%		$1,000.00		$1,075.69		$4.27
R4	Hypothetical (h)		0.83%		$1,000.00		$1,020.68		$4.16
R6	Actual		0.73%		$1,000.00		$1,076.29		$3.76
R6	Hypothetical (h)		0.73%		$1,000.00		$1,021.17		$3.66
529A	Actual		1.11%		$1,000.00		$1,074.61		$5.71
529A	Hypothetical (h)		1.11%		$1,000.00		$1,019.29		$5.56
529B	Actual		1.88%		$1,000.00		$1,070.73		$9.65
529B	Hypothetical (h)		1.88%		$1,000.00		$1,015.47		$9.39
529C	Actual		1.87%		$1,000.00		$1,070.32		$9.60
529C	Hypothetical (h)		1.87%		$1,000.00		$1,015.52		$9.35

(h)	5% class return per year before expenses.

(p)

Notes to Expense Table

Each class with a Rule 12b-1 service fee is subject to a rebate of a portion of such fee. Such rebates are included in the expense ratios above. For Class 529A and Class 529C shares, this rebate reduced the expense ratios above by 0.02% and 0.01%, respectively. See Note 3 in the Notes to Financial Statements for additional information.

PORTFOLIO OF INVESTMENTS

2/28/18 (unaudited)

The Portfolio of Investments is a complete list of all securities owned by your fund. It is categorized by broad-based asset classes.


Common Stocks - 98.8%
Issuer	Shares/Par		Value ($)
Airlines - 1.0%
Aena S.A.		216,834	$	44,102,954
Malaysia Airports Holdings Berhad		15,702,600		34,876,849

			$	78,979,803
Alcoholic Beverages - 0.5%
AmBev S.A., ADR		6,065,904	$	40,944,852

Apparel Manufacturers - 1.4%
LVMH Moet Hennessy Louis Vuitton SE		373,108	$	111,476,241

Automotive - 3.5%
GKN PLC		16,096,024	$	97,013,792
Koito Manufacturing Co. Ltd.		1,384,800		95,563,588
USS Co. Ltd.		4,564,600		93,988,046

			$	286,565,426
Broadcasting - 1.0%
WPP PLC		4,337,503	$	82,845,773

Brokerage & Asset Managers - 0.6%
TMX Group Ltd.		883,687	$	52,827,018

Business Services - 2.5%
Cerved Information Solutions S.p.A.		1,893,960	$	24,391,198
Cognizant Technology Solutions Corp., “A”		1,589,911		130,404,500
Nomura Research Institute Ltd.		1,240,900		55,622,818

			$	210,418,516
Chemicals - 0.5%
Orica Ltd.		2,583,757	$	37,236,817

Computer Software - 0.6%
Check Point Software Technologies Ltd. (a)		457,375	$	47,516,689

Computer Software - Systems - 2.3%
Amadeus IT Group S.A.		1,151,488	$	84,513,197
EPAM Systems, Inc. (a)		573,465		64,870,361
Hitachi Ltd.		5,615,000		42,596,026

			$	191,979,584

Portfolio of Investments (unaudited) – continued


Issuer	Shares/Par		Value ($)
Common Stocks - continued
Construction - 2.2%
Techtronic Industries Co. Ltd.		12,643,500	$	78,377,310
Toto Ltd.		1,973,400		103,467,712

			$	181,845,022
Consumer Products - 2.8%
L’Oréal		475,303	$	102,440,075
Reckitt Benckiser Group PLC		1,571,442		124,588,917

			$	227,028,992
Consumer Services - 0.3%
Ctrip.com International Ltd., ADR (a)		602,988	$	27,725,388

Containers - 1.0%
Brambles Ltd.		11,578,020	$	85,983,609

Electrical Equipment - 2.7%
Legrand S.A.		793,724	$	62,196,837
Schneider Electric S.A. (a)		1,899,232		164,501,687

			$	226,698,524
Electronics - 2.6%
Broadcom Corp.		116,069	$	28,606,366
Mellanox Technologies Ltd. (a)		578,682		39,813,321
Samsung Electronics Co. Ltd.		11,997		26,001,334
Silicon Motion Technology Corp., ADR		526,200		24,662,994
Taiwan Semiconductor Manufacturing Co. Ltd.		11,175,326		91,779,263

			$	210,863,278
Energy - Independent - 1.6%
Cairn Energy PLC (a)		10,082,986	$	25,760,126
Caltex Australia Ltd.		1,902,157		51,593,158
Oil Search Ltd.		8,716,333		50,712,503

			$	128,065,787
Energy - Integrated - 2.7%
BP PLC		15,844,844	$	102,781,585
Eni S.p.A.		4,099,405		68,241,871
Galp Energia SGPS S.A., “B”		3,098,549		55,994,655

			$	227,018,111
Food & Beverages - 4.6%
Danone S.A.		1,673,518	$	133,520,393
Nestle S.A.		3,088,374		245,835,035

			$	379,355,428

Portfolio of Investments (unaudited) – continued


Issuer	Shares/Par		Value ($)
Common Stocks - continued
Food & Drug Stores - 1.6%
Booker Group PLC		15,738,798	$	49,006,397
Sundrug Co. Ltd.		1,828,900		84,167,491

			$	133,173,888
Gaming & Lodging - 0.5%
Paddy Power Betfair PLC		384,757	$	44,526,605

General Merchandise - 0.1%
Dollarama, Inc.		75,047	$	8,734,624

Insurance - 5.7%
AIA Group Ltd.		18,983,200	$	157,625,831
Aon PLC		550,142		77,195,925
Hiscox Ltd.		3,580,007		68,270,373
Swiss Re Ltd.		602,807		61,595,590
Zurich Insurance Group AG		316,559		104,436,901

			$	469,124,620
Internet - 1.5%
Alibaba Group Holding Ltd., ADR (a)		208,500	$	38,810,190
NAVER Corp.		83,995		61,957,349
Scout24 AG		589,027		25,918,912

			$	126,686,451
Machinery & Tools - 5.4%
Daikin Industries Ltd.		1,030,800	$	121,189,821
GEA Group AG		1,845,461		87,694,475
Kubota Corp.		6,189,400		111,976,250
Ritchie Bros. Auctioneers, Inc.		1,207,418		39,143,227
Schindler Holding AG		369,312		86,514,810

			$	446,518,583
Major Banks - 7.8%
Barclays PLC		36,699,274	$	107,709,256
BNP Paribas		1,890,242		149,459,959
Erste Group Bank AG		1,889,329		95,956,194
Mitsubishi UFJ Financial Group, Inc.		17,725,300		125,173,172
UBS AG		8,599,123		163,033,709

			$	641,332,290
Medical & Health Technology & Services - 0.4%
Sonic Healthcare Ltd.		1,934,319	$	36,668,144

Medical Equipment - 1.2%
Terumo Corp.		1,820,300	$	98,440,705

Portfolio of Investments (unaudited) – continued


Issuer	Shares/Par		Value ($)
Common Stocks - continued
Metals & Mining - 1.3%
Rio Tinto Ltd.		1,986,746	$	106,418,526

Natural Gas - Distribution - 0.7%
China Resources Gas Group Ltd.		16,256,000	$	54,583,383

Natural Gas - Pipeline - 1.2%
APA Group		7,595,145	$	47,015,100
APA Group (a)		444,802		2,680,841
Enbridge, Inc.		1,495,891		47,574,277

			$	97,270,218
Network & Telecom - 0.5%
LM Ericsson Telephone Co., “B”		6,350,758	$	42,459,580

Oil Services - 0.5%
Schlumberger Ltd.		664,168	$	43,595,988

Other Banks & Diversified Financials - 8.7%
Aeon Credit Service Co. Ltd.		3,926,500	$	91,078,675
AIB Group PLC		10,426,331		68,688,680
DnB NOR A.S.A.		2,732,872		53,646,473
HDFC Bank Ltd.		2,166,630		63,196,278
Intesa Sanpaolo S.p.A.		29,787,875		111,870,756
Julius Baer Group Ltd.		1,451,345		93,857,090
Jyske Bank A.S.		1,115,983		65,744,863
KBC Groep N.V.		1,167,522		109,804,314
Mastercard, Inc., “A”		346,423		60,887,306

			$	718,774,435
Pharmaceuticals - 7.7%
Bayer AG		1,628,559	$	190,971,284
Novo Nordisk A.S., “B”		2,798,361		144,264,749
Roche Holding AG		834,393		193,469,578
Santen Pharmaceutical Co. Ltd.		6,981,300		111,521,672

			$	640,227,283
Printing & Publishing - 1.2%
RELX N.V.		4,867,338	$	99,696,475

Real Estate - 2.4%
Grand City Properties S.A.		3,611,577	$	80,940,510
LEG Immobilien AG		1,104,462		115,069,965

			$	196,010,475

Portfolio of Investments (unaudited) – continued


Issuer	Shares/Par		Value ($)
Common Stocks - continued
Restaurants - 0.4%
Yum China Holdings, Inc.		838,147	$	36,308,528

Specialty Chemicals - 7.2%
Akzo Nobel N.V.		1,414,157	$	136,978,401
Croda International PLC		1,685,019		106,694,573
Linde AG (a)		652,339		146,715,631
Nitto Denko Corp.		575,800		47,433,860
Sika AG		10,468		86,074,055
Symrise AG		858,676		69,809,692

			$	593,706,212
Specialty Stores - 1.1%
Dufry AG (a)		274,568	$	39,354,194
Just Eat PLC (a)		4,361,694		52,342,081

			$	91,696,275
Telecommunications - Wireless - 3.7%
Advanced Info Service PLC		8,658,300	$	54,476,402
Cellnex Telecom S.A.U.		2,725,322		69,917,417
KDDI Corp.		3,754,600		92,231,375
SoftBank Corp.		1,077,300		88,880,337

			$	305,505,531
Telephone Services - 0.4%
Com Hem Holding AB		2,043,818	$	33,701,917

Tobacco - 1.1%
Japan Tobacco, Inc.		3,190,800	$	90,929,846

Trucking - 0.7%
Yamato Holdings Co. Ltd.		2,463,300	$	61,406,446

Utilities - Electric Power - 1.4%
CLP Holdings Ltd.		6,608,000	$	66,595,293
Iberdrola S.A.		6,982,220		51,412,131

			$	118,007,424
Total Common Stocks (Identified Cost, $6,901,525,673)			$	8,170,879,310

Investment Companies (h) - 1.3%
Money Market Funds - 1.3%
MFS Institutional Money Market Portfolio, 1.52% (v) (Identified Cost, $110,548,948)		110,557,124	$	110,546,068

Other Assets, Less Liabilities - (0.1)%				(10,503,658	)
Net Assets - 100.0%			$	8,270,921,720

Portfolio of Investments (unaudited) – continued

(a)	Non-income producing security.

(h)

(v)	Affiliated issuer that is available only to investment companies managed by MFS. The rate quoted for the MFS Institutional Money Market Portfolio is the annualized seven-day yield of the fund at period end.

The following abbreviations are used in this report and are defined:

ADR

American Depositary Receipt

PLC

Public Limited Company

See Notes to Financial Statements

Financial Statements

STATEMENT OF ASSETS AND LIABILITIES

At 2/28/18 (unaudited)

This statement represents your fund’s balance sheet, which details the assets and liabilities comprising the total value of the fund.


Assets
Investments in unaffiliated issuers, at value (identified cost, $6,901,525,673)	$8,170,879,310
Investments in affiliated issuers, at value (identified cost, $110,548,948)	110,546,068
Foreign currency, at value (identified cost, $281,231)	281,862
Receivables for
Investments sold	10,231,629
Fund shares sold	14,283,422
Interest and dividends	24,002,909
Other assets	27,119
Total assets	$8,330,252,319
Liabilities
Payables for
Investments purchased	$50,241,744
Fund shares reacquired	6,617,008
Payable to affiliates
Investment adviser	319,233
Shareholder servicing costs	546,333
Distribution and service fees	17,514
Program manager fee	46
Payable for independent Trustees’ compensation	788
Deferred country tax expense payable	1,173,777
Accrued expenses and other liabilities	414,156
Total liabilities	$59,330,599
Net assets	$8,270,921,720
Net assets consist of
Paid-in capital	$7,271,954,636
Unrealized appreciation (depreciation) (net of $1,173,777 deferred country tax)	1,269,007,512
Accumulated net realized gain (loss)	(278,079,773	)
Undistributed net investment income	8,039,345
Net assets	$8,270,921,720
Shares of beneficial interest outstanding	429,449,055

Statement of Assets and Liabilities (unaudited) – continued


	Net assets		Shares outstanding		Net asset value per share (a)
Class A		$699,180,505		36,194,194		$19.32
Class B		5,753,065		308,223		18.67
Class C		46,970,344		2,583,888		18.18
Class I		743,242,673		37,214,812		19.97
Class R1		2,176,266		121,560		17.90
Class R2		161,114,973		8,627,920		18.67
Class R3		88,075,801		4,607,383		19.12
Class R4		64,448,432		3,331,581		19.34
Class R6		6,443,651,026		335,580,596		19.20
Class 529A		11,836,648		624,642		18.95
Class 529B		378,197		21,116		17.91
Class 529C		4,093,790		233,140		17.56

(a)

Maximum offering price per share was equal to the net asset value per share for all share classes, except for Classes A and 529A, for which the maximum offering prices per share were $20.50 [100 / 94.25 x $19.32] and $20.11 [100 / 94.25 x $18.95], respectively. On sales of $50,000 or more, the maximum offering prices of Class A and Class 529A shares are reduced. A contingent deferred sales charge may be imposed on redemptions of Class A, Class B, Class C, Class 529B, and Class 529C shares. Redemption price per share was equal to the net asset value per share for Classes I, R1, R2, R3, R4, R6, and 529A. Net asset value per share is calculated using actual net assets and shares outstanding rather than amounts that have been rounded for presentation purposes.

See Notes to Financial Statements

Financial Statements

STATEMENT OF OPERATIONS

Six months ended 2/28/18 (unaudited)

This statement describes how much your fund earned in investment income and accrued in expenses. It also describes any gains and/or losses generated by fund operations.


Net investment income (loss)
Income
Dividends	$43,083,663
Dividends from affiliated issuers	568,623
Income on securities loaned	152,353
Interest	202
Foreign taxes withheld	(3,846,948	)
Total investment income	$39,957,893
Expenses
Management fee	$27,617,115
Distribution and service fees	1,666,967
Shareholder servicing costs	1,312,389
Program manager fees	6,043
Administrative services fee	309,131
Independent Trustees’ compensation	46,400
Custodian fee	530,126
Shareholder communications	165,777
Audit and tax fees	37,114
Legal fees	36,861
Miscellaneous	179,840
Total expenses	$31,907,763
Reduction of expenses by investment adviser and distributor	(347,803	)
Net expenses	$31,559,960
Net investment income (loss)	$8,397,933
Realized and unrealized gain (loss)
Realized gain (loss) (identified cost basis)
Unaffiliated issuers	$130,808,023
Affiliated issuers	2,771
Foreign currency	382,036
Net realized gain (loss)	$131,192,830
Change in unrealized appreciation (depreciation)
Unaffiliated issuers (net of $448,600 increase in deferred country tax)	$428,880,989
Affiliated issuers	(2,578	)
Translation of assets and liabilities in foreign currencies	161,068
Net unrealized gain (loss)	$429,039,479
Net realized and unrealized gain (loss)	$560,232,309
Change in net assets from operations	$568,630,242

See Notes to Financial Statements

Financial Statements

STATEMENTS OF CHANGES IN NET ASSETS

These statements describe the increases and/or decreases in net assets resulting from operations, any distributions, and any shareholder transactions.


Change in net assets	Six months ended 2/28/18 (unaudited)			Year ended 8/31/17
From operations
Net investment income (loss)		$8,397,933			$111,047,852
Net realized gain (loss)		131,192,830			147,136,723
Net unrealized gain (loss)		429,039,479			806,246,044
Change in net assets from operations		$568,630,242			$1,064,430,619
Distributions declared to shareholders
From net investment income		$(107,400,473	)		$(123,095,420	)
Change in net assets from fund share transactions		$428,523,386			$1,950,464
Total change in net assets		$889,753,155			$943,285,663
Net assets
At beginning of period		7,381,168,565			6,437,882,902
At end of period (including undistributed net investment income of $8,039,345 and $107,041,885, respectively)		$8,270,921,720			$7,381,168,565

See Notes to Financial Statements

Financial Statements

FINANCIAL HIGHLIGHTS


	Six months ended 2/28/18			Year ended
Class A	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14			8/31/13
	(unaudited)

Net asset value, beginning of period		$18.16			$15.83			$16.34			$18.06			$16.25			$14.25
Income (loss) from investment operations
Net investment income (loss) (d)		$(0.01	)		$0.20	(c)		$0.25			$0.26			$0.40			$0.26
Net realized and unrealized gain (loss)		1.37			2.39			(0.50	)		(1.60	)		1.64			2.01
Total from investment operations		$1.36			$2.59			$(0.25	)		$(1.34	)		$2.04			$2.27
Less distributions declared to shareholders
From net investment income		$(0.20	)		$(0.26	)		$(0.26	)		$(0.38	)		$(0.23	)		$(0.27	)
Net asset value, end of period (x)		$19.32			$18.16			$15.83			$16.34			$18.06			$16.25
Total return (%) (r)(s)(t)(x)		7.51	(n)		16.66	(c)		(1.50	)		(7.44	)		12.60			16.08
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.09	(a)		1.12	(c)		1.14			1.13			1.13			1.18
Expenses after expense reductions (f)		1.08	(a)		1.10	(c)		1.11			1.09			1.11			1.18
Net investment income (loss)		(0.05	)(a)(l)		1.25	(c)		1.62			1.53			2.24			1.65
Portfolio turnover		12	(n)		33			40			28			27			32
Net assets at end of period (000 omitted)		$699,181			$693,538			$971,630			$1,178,013			$1,184,927			$1,108,795

See Notes to Financial Statements

Financial Highlights – continued


	Six months ended 2/28/18			Year ended
Class B	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14			8/31/13
	(unaudited)

Net asset value, beginning of period		$17.48			$15.21			$15.65			$17.26			$15.52			$13.59
Income (loss) from investment operations
Net investment income (loss) (d)		$(0.07	)		$0.10	(c)		$0.12			$0.12			$0.25			$0.12
Net realized and unrealized gain (loss)		1.31			2.28			(0.47	)		(1.52	)		1.57			1.94
Total from investment operations		$1.24			$2.38			$(0.35	)		$(1.40	)		$1.82			$2.06
Less distributions declared to shareholders
From net investment income		$(0.05	)		$(0.11	)		$(0.09	)		$(0.21	)		$(0.08	)		$(0.13	)
Net asset value, end of period (x)		$18.67			$17.48			$15.21			$15.65			$17.26			$15.52
Total return (%) (r)(s)(t)(x)		7.10	(n)		15.77	(c)		(2.20	)		(8.15	)		11.77			15.27
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.84	(a)		1.87	(c)		1.89			1.88			1.88			1.93
Expenses after expense reductions (f)		1.83	(a)		1.85	(c)		1.86			1.84			1.86			1.93
Net investment income (loss)		(0.80	)(a)(l)		0.61	(c)		0.82			0.70			1.46			0.83
Portfolio turnover		12	(n)		33			40			28			27			32
Net assets at end of period (000 omitted)		$5,753			$6,228			$7,967			$11,228			$16,932			$19,751

See Notes to Financial Statements

Financial Highlights – continued


	Six months ended 2/28/18			Year ended
Class C	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14			8/31/13
	(unaudited)

Net asset value, beginning of period		$17.03			$14.85			$15.31			$16.93			$15.26			$13.39
Income (loss) from investment operations
Net investment income (loss) (d)		$(0.07	)		$0.10	(c)		$0.12			$0.12			$0.25			$0.13
Net realized and unrealized gain (loss)		1.28			2.21			(0.45	)		(1.50	)		1.54			1.90
Total from investment operations		$1.21			$2.31			$(0.33	)		$(1.38	)		$1.79			$2.03
Less distributions declared to shareholders
From net investment income		$(0.06	)		$(0.13	)		$(0.13	)		$(0.24	)		$(0.12	)		$(0.16	)
Net asset value, end of period (x)		$18.18			$17.03			$14.85			$15.31			$16.93			$15.26
Total return (%) (r)(s)(t)(x)		7.09	(n)		15.74	(c)		(2.16	)		(8.17	)		11.74			15.22
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.84	(a)		1.87	(c)		1.89			1.88			1.88			1.93
Expenses after expense reductions (f)		1.83	(a)		1.85	(c)		1.86			1.84			1.86			1.93
Net investment income (loss)		(0.80	)(a)(l)		0.64	(c)		0.85			0.76			1.50			0.87
Portfolio turnover		12	(n)		33			40			28			27			32
Net assets at end of period (000 omitted)		$46,970			$48,570			$62,124			$77,442			$91,487			$86,793

See Notes to Financial Statements

Financial Highlights – continued


	Six months ended 2/28/18			Year ended
Class I	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14			8/31/13
	(unaudited)

Net asset value, beginning of period		$18.79			$16.38			$16.90			$18.66			$16.78			$14.71
Income (loss) from investment operations
Net investment income (loss) (d)		$0.02			$0.30	(c)		$0.30			$0.32			$0.46			$0.31
Net realized and unrealized gain (loss)		1.40			2.42			(0.51	)		(1.66	)		1.69			2.06
Total from investment operations		$1.42			$2.72			$(0.21	)		$(1.34	)		$2.15			$2.37
Less distributions declared to shareholders
From net investment income		$(0.24	)		$(0.31	)		$(0.31	)		$(0.42	)		$(0.27	)		$(0.30	)
Net asset value, end of period (x)		$19.97			$18.79			$16.38			$16.90			$18.66			$16.78
Total return (%) (r)(s)(t)(x)		7.59	(n)		16.95	(c)		(1.24	)		(7.19	)		12.89			16.32
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		0.84	(a)		0.87	(c)		0.89			0.88			0.88			0.93
Expenses after expense reductions (f)		0.83	(a)		0.86	(c)		0.86			0.84			0.86			0.93
Net investment income (loss)		0.19	(a)(l)		1.79	(c)		1.86			1.80			2.51			1.89
Portfolio turnover		12	(n)		33			40			28			27			32
Net assets at end of period (000 omitted)		$743,243			$1,099,134			$2,187,011			$2,410,936			$2,194,432			$1,834,498

See Notes to Financial Statements

Financial Highlights – continued


	Six months ended 2/28/18			Year ended
Class R1	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14			8/31/13
	(unaudited)

Net asset value, beginning of period		$16.80			$14.63			$15.08			$16.69			$15.02			$13.17
Income (loss) from investment operations
Net investment income (loss) (d)		$(0.07	)		$0.09	(c)		$0.11			$0.11			$0.24			$0.12
Net realized and unrealized gain (loss)		1.26			2.20			(0.44	)		(1.47	)		1.52			1.87
Total from investment operations		$1.19			$2.29			$(0.33	)		$(1.36	)		$1.76			$1.99
Less distributions declared to shareholders
From net investment income		$(0.09	)		$(0.12	)		$(0.12	)		$(0.25	)		$(0.09	)		$(0.14	)
Net asset value, end of period (x)		$17.90			$16.80			$14.63			$15.08			$16.69			$15.02
Total return (%) (r)(s)(t)(x)		7.06	(n)		15.79	(c)		(2.19	)		(8.18	)		11.73			15.24
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.84	(a)		1.87	(c)		1.89			1.88			1.88			1.93
Expenses after expense reductions (f)		1.83	(a)		1.85	(c)		1.86			1.84			1.86			1.93
Net investment income (loss)		(0.81	)(a)(l)		0.61	(c)		0.78			0.72			1.47			0.85
Portfolio turnover		12	(n)		33			40			28			27			32
Net assets at end of period (000 omitted)		$2,176			$2,089			$2,418			$3,509			$4,243			$4,034

See Notes to Financial Statements

Financial Highlights – continued


	Six months ended 2/28/18			Year ended
Class R2	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14			8/31/13
	(unaudited)

Net asset value, beginning of period		$17.55			$15.31			$15.80			$17.48			$15.75			$13.83
Income (loss) from investment operations
Net investment income (loss) (d)		$(0.03	)		$0.17	(c)		$0.21			$0.22			$0.36			$0.21
Net realized and unrealized gain (loss)		1.31			2.30			(0.48	)		(1.56	)		1.57			1.95
Total from investment operations		$1.28			$2.47			$(0.27	)		$(1.34	)		$1.93			$2.16
Less distributions declared to shareholders
From net investment income		$(0.16	)		$(0.23	)		$(0.22	)		$(0.34	)		$(0.20	)		$(0.24	)
Net asset value, end of period (x)		$18.67			$17.55			$15.31			$15.80			$17.48			$15.75
Total return (%) (r)(s)(t)(x)		7.30	(n)		16.37	(c)		(1.69	)		(7.69	)		12.32			15.79
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.34	(a)		1.37	(c)		1.39			1.38			1.38			1.43
Expenses after expense reductions (f)		1.33	(a)		1.35	(c)		1.36			1.34			1.36			1.43
Net investment income (loss)		(0.34	)(a)(l)		1.10	(c)		1.38			1.29			2.06			1.41
Portfolio turnover		12	(n)		33			40			28			27			32
Net assets at end of period (000 omitted)		$161,115			$132,988			$152,133			$169,812			$182,466			$136,444

See Notes to Financial Statements

Financial Highlights – continued


	Six months ended 2/28/18			Year ended
Class R3	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14			8/31/13
	(unaudited)

Net asset value, beginning of period		$17.98			$15.67			$16.16			$17.86			$16.08			$14.10
Income (loss) from investment operations
Net investment income (loss) (d)		$(0.00	)(w)		$0.22	(c)		$0.24			$0.25			$0.40			$0.25
Net realized and unrealized gain (loss)		1.34			2.35			(0.48	)		(1.58	)		1.61			2.00
Total from investment operations		$1.34			$2.57			$(0.24	)		$(1.33	)		$2.01			$2.25
Less distributions declared to shareholders
From net investment income		$(0.20	)		$(0.26	)		$(0.25	)		$(0.37	)		$(0.23	)		$(0.27	)
Net asset value, end of period (x)		$19.12			$17.98			$15.67			$16.16			$17.86			$16.08
Total return (%) (r)(s)(t)(x)		7.48	(n)		16.67	(c)		(1.47	)		(7.44	)		12.56			16.13
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.09	(a)		1.12	(c)		1.14			1.13			1.13			1.18
Expenses after expense reductions (f)		1.08	(a)		1.10	(c)		1.11			1.09			1.11			1.18
Net investment income (loss)		(0.05	)(a)(l)		1.37	(c)		1.59			1.46			2.28			1.63
Portfolio turnover		12	(n)		33			40			28			27			32
Net assets at end of period (000 omitted)		$88,076			$91,653			$126,980			$165,656			$229,232			$195,358

See Notes to Financial Statements

Financial Highlights – continued


	Six months ended 2/28/18			Year ended
Class R4	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14			8/31/13
	(unaudited)

Net asset value, beginning of period		$18.21			$15.86			$16.36			$18.09			$16.27			$14.26
Income (loss) from investment operations
Net investment income (loss) (d)		$0.02			$0.28	(c)		$0.30			$0.29			$0.45			$0.25
Net realized and unrealized gain (loss)		1.35			2.35			(0.50	)		(1.60	)		1.63			2.06
Total from investment operations		$1.37			$2.63			$(0.20	)		$(1.31	)		$2.08			$2.31
Less distributions declared to shareholders
From net investment income		$(0.24	)		$(0.28	)		$(0.30	)		$(0.42	)		$(0.26	)		$(0.30	)
Net asset value, end of period (x)		$19.34			$18.21			$15.86			$16.36			$18.09			$16.27
Total return (%) (r)(s)(t)(x)		7.57	(n)		16.92	(c)		(1.20	)		(7.26	)		12.87			16.42
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		0.84	(a)		0.87	(c)		0.89			0.88			0.88			0.93
Expenses after expense reductions (f)		0.83	(a)		0.86	(c)		0.86			0.85			0.86			0.93
Net investment income (loss)		0.20	(a)(l)		1.73	(c)		1.93			1.70			2.54			1.60
Portfolio turnover		12	(n)		33			40			28			27			32
Net assets at end of period (000 omitted)		$64,448			$63,884			$148,243			$343,475			$546,069			$470,915

See Notes to Financial Statements

Financial Highlights – continued


	Six months ended 2/28/18			Year ended
Class R6	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14			8/31/13
	(unaudited)

Net asset value, beginning of period		$18.10			$15.79			$16.30			$18.02			$16.21			$14.20
Income (loss) from investment operations
Net investment income (loss) (d)		$0.03			$0.28	(c)		$0.31			$0.32			$0.46			$0.33
Net realized and unrealized gain (loss)		1.35			2.36			(0.50	)		(1.60	)		1.64			1.99
Total from investment operations		$1.38			$2.64			$(0.19	)		$(1.28	)		$2.10			$2.32
Less distributions declared to shareholders
From net investment income		$(0.28	)		$(0.33	)		$(0.32	)		$(0.44	)		$(0.29	)		$(0.31	)
Net asset value, end of period (x)		$19.20			$18.10			$15.79			$16.30			$18.02			$16.21
Total return (%) (r)(s)(t)(x)		7.63	(n)		17.07	(c)		(1.13	)		(7.13	)		13.01			16.50
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		0.74	(a)		0.77	(c)		0.79			0.79			0.79			0.81
Expenses after expense reductions (f)		0.73	(a)		0.76	(c)		0.76			0.75			0.77			0.81
Net investment income (loss)		0.28	(a)(l)		1.72	(c)		2.02			1.88			2.62			2.09
Portfolio turnover		12	(n)		33			40			28			27			32
Net assets at end of period (000 omitted)		$6,443,651			$5,228,377			$2,766,544			$3,010,863			$2,955,339			$2,331,325

See Notes to Financial Statements

Financial Highlights – continued


	Six months ended 2/28/18			Year ended
Class 529A	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14			8/31/13
	(unaudited)

Net asset value, beginning of period		$17.84			$15.61			$16.12			$17.81			$16.03			$14.06
Income (loss) from investment operations
Net investment income (loss) (d)		$(0.01	)		$0.23	(c)		$0.19			$0.26			$0.39			$0.25
Net realized and unrealized gain (loss)		1.34			2.31			(0.44	)		(1.58	)		1.62			1.98
Total from investment operations		$1.33			$2.54			$(0.25	)		$(1.32	)		$2.01			$2.23
Less distributions declared to shareholders
From net investment income		$(0.22	)		$(0.31	)		$(0.26	)		$(0.37	)		$(0.23	)		$(0.26	)
Net asset value, end of period (x)		$18.95			$17.84			$15.61			$16.12			$17.81			$16.03
Total return (%) (r)(s)(t)(x)		7.46	(n)		16.60	(c)		(1.52	)		(7.43	)		12.57			16.05
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.17	(a)		1.22	(c)		1.23			1.23			1.23			1.28
Expenses after expense reductions (f)		1.11	(a)		1.13	(c)		1.13			1.12			1.14			1.21
Net investment income (loss)		(0.10	)(a)(l)		1.39	(c)		1.22			1.51			2.22			1.62
Portfolio turnover		12	(n)		33			40			28			27			32
Net assets at end of period (000 omitted)		$11,837			$10,464			$9,101			$2,419			$2,428			$2,105

See Notes to Financial Statements

Financial Highlights – continued


	Six months ended 2/28/18			Year ended
Class 529B	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14			8/31/13
	(unaudited)

Net asset value, beginning of period		$16.79			$14.78			$15.19			$16.80			$15.14			$13.25
Income (loss) from investment operations
Net investment income (loss) (d)		$(0.07	)		$0.09	(c)		$0.05			$0.10			$0.25			$0.12
Net realized and unrealized gain (loss)		1.26			2.18			(0.39	)		(1.47	)		1.52			1.88
Total from investment operations		$1.19			$2.27			$(0.34	)		$(1.37	)		$1.77			$2.00
Less distributions declared to shareholders
From net investment income		$(0.07	)		$(0.26	)		$(0.07	)		$(0.24	)		$(0.11	)		$(0.11	)
Net asset value, end of period (x)		$17.91			$16.79			$14.78			$15.19			$16.80			$15.14
Total return (%) (r)(s)(t)(x)		7.07	(n)		15.68	(c)		(2.25	)		(8.17	)		11.71			15.15
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.92	(a)		1.97	(c)		1.98			1.98			1.98			2.03
Expenses after expense reductions (f)		1.88	(a)		1.90	(c)		1.90			1.89			1.91			1.98
Net investment income (loss)		(0.85	)(a)(l)		0.58	(c)		0.37			0.63			1.49			0.82
Portfolio turnover		12	(n)		33			40			28			27			32
Net assets at end of period (000 omitted)		$378			$386			$434			$138			$192			$188

See Notes to Financial Statements

Financial Highlights – continued


	Six months ended 2/28/18			Year ended
Class 529C	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14			8/31/13
	(unaudited)

Net asset value, beginning of period		$16.51			$14.53			$15.01			$16.61			$14.98			$13.17
Income (loss) from investment operations
Net investment income (loss) (d)		$(0.07	)		$0.10	(c)		$0.07			$0.11			$0.23			$0.12
Net realized and unrealized gain (loss)		1.23			2.15			(0.41	)		(1.46	)		1.52			1.86
Total from investment operations		$1.16			$2.25			$(0.34	)		$(1.35	)		$1.75			$1.98
Less distributions declared to shareholders
From net investment income		$(0.11	)		$(0.27	)		$(0.14	)		$(0.25	)		$(0.12	)		$(0.17	)
Net asset value, end of period (x)		$17.56			$16.51			$14.53			$15.01			$16.61			$14.98
Total return (%) (r)(s)(t)(x)		7.03	(n)		15.78	(c)		(2.28	)		(8.17	)		11.68			15.17
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.92	(a)		1.97	(c)		1.99			1.98			1.98			2.03
Expenses after expense reductions (f)		1.87	(a)		1.89	(c)		1.90			1.89			1.91			1.98
Net investment income (loss)		(0.85	)(a)(l)		0.63	(c)		0.47			0.72			1.43			0.81
Portfolio turnover		12	(n)		33			40			28			27			32
Net assets at end of period (000 omitted)		$4,094			$3,856			$3,298			$980			$1,098			$950

(a)	Annualized.

(c)	Amount reflects a one-time reimbursement of expenses by the custodian (or former custodian) without which net investment income and performance would be lower and expenses would be higher.

(d)	Per share data is based on average shares outstanding.

(f)	Ratios do not reflect reductions from fees paid indirectly, if applicable.

(l)	Recognition of net investment income by the fund may be affected by the timing of the declaration of dividends by companies in which the fund invests and the actual annual net investment income ratio may differ.

(n)	Not annualized.

(r)	Certain expenses have been reduced without which performance would have been lower.

(s)	From time to time the fund may receive proceeds from litigation settlements, without which performance would be lower.

(t)	Total returns do not include any applicable sales charges.

(w)	Per share amount was less than $0.01.

(x)	The net asset values and total returns have been calculated on net assets which include adjustments made in accordance with U.S. generally accepted accounting principles required at period end for financial reporting purposes.

See Notes to Financial Statements

NOTES TO FINANCIAL STATEMENTS

(unaudited)

(1) Business and Organization

MFS Research International Fund (the fund) is a diversified series of MFS Series Trust I (the trust). The trust is organized as a Massachusetts business trust and is registered under the Investment Company Act of 1940, as amended, as an open-end management investment company.

(2) Significant Accounting Policies

Notes to Financial Statements (unaudited) – continued

services can utilize both transaction data and market information such as yield, quality, coupon rate, maturity, type of issue, trading characteristics, and other market data. The values of foreign securities and other assets and liabilities expressed in foreign currencies are converted to U.S. dollars using the mean of bid and asked prices for rates provided by a third-party pricing service.

Notes to Financial Statements (unaudited) – continued

unobservable inputs, which may include the adviser’s own assumptions in determining the fair value of investments. The following is a summary of the levels used as of February 28, 2018 in valuing the fund’s assets or liabilities:


Financial Instruments	Level 1		Level 2		Level 3		Total
Equity Securities:
Japan		$98,440,705		$1,417,227,136		$—		$1,515,667,841
Switzerland		61,595,590		1,012,575,371		—		1,074,170,961
United Kingdom		97,013,792		826,417,606		—		923,431,398
France		—		723,595,193		—		723,595,193
Germany		315,350,616		401,769,854		—		717,120,470
United States		445,373,768		—		—		445,373,768
Australia		—		311,890,172		—		311,890,172
Hong Kong		—		302,598,433		—		302,598,433
Spain		—		249,945,699		—		249,945,699
Other Countries		522,289,718		1,384,795,657		—		1,907,085,375
Mutual Funds		110,546,068		—		—		110,546,068
Total		$1,650,610,257		$6,630,815,121		$—		$8,281,425,378

For further information regarding security characteristics, see the Portfolio of Investments.

Of the level 2 investments presented above, equity investments amounting to $6,236,490,355 would have been considered level 1 investments at the beginning of the period. Of the level 1 investments presented above, equity investments amounting to $54,476,402 would have been considered level 2 investments at the beginning of the period. The primary reason for changes in the classifications between levels 1 and 2 occurs when foreign equity securities are fair valued using other observable market-based inputs in place of the closing exchange price due to events occurring after the close of the exchange or market on which the investment is principally traded. The fund’s foreign equity securities may often be valued using other observable market-based inputs. The fund’s policy is to recognize transfers between the levels as of the end of the period.

Notes to Financial Statements (unaudited) – continued

fund and the related securities must be returned within the earlier of the standard trade settlement period for such securities or within three business days. The loans are collateralized by cash and/or U.S. Treasury and federal agency obligations in an amount typically at least equal to the market value of the securities loaned. On loans collateralized by cash, the cash collateral is invested in a money market fund. The market value of the loaned securities is determined at the close of business of the fund and any additional required collateral is delivered to the fund on the next business day. State Street provides the fund with indemnification against Borrower default. In the event of Borrower default, State Street will, for the benefit of the fund, either purchase securities identical to those loaned or, when such purchase is commercially impracticable, pay the fund the market value of the loaned securities. In return, State Street assumes the fund’s rights to the related collateral. If the collateral value is less than the cost to purchase identical securities, State Street is responsible for the shortfall, but only to the extent that such shortfall is not due to a decline in collateral value resulting from collateral reinvestment for which the fund bears the risk of loss. A portion of the income generated upon investment of the collateral is remitted to the Borrowers, and the remainder is allocated between the fund and the lending agent. On loans collateralized by U.S. Treasury and/or federal agency obligations, a fee is received from the Borrower, and is allocated between the fund and the lending agent. Income from securities lending is separately reported in the Statement of Operations. The dividend and interest income earned on the securities loaned is accounted for in the same manner as other dividend and interest income. At February 28, 2018, there were no securities on loan or collateral outstanding.

Tax Matters and Distributions – The fund intends to qualify as a regulated investment company, as defined under Subchapter M of the Internal Revenue Code,

Notes to Financial Statements (unaudited) – continued

Book/tax differences primarily relate to wash sale loss deferrals.


	Year ended 8/31/17
Ordinary income (including any short-term capital gains)		$123,095,420

The federal tax cost and the tax basis components of distributable earnings were as follows:


As of 2/28/18
Cost of investments	$7,037,574,445
Gross appreciation	1,486,227,180
Gross depreciation	(242,376,247	)
Net unrealized appreciation (depreciation)	$1,243,850,933

As of 8/31/17
Undistributed ordinary income	107,377,778
Capital loss carryforwards	(384,347,670	)
Other temporary differences	210,045
Net unrealized appreciation (depreciation)	814,497,162

The aggregate cost above includes prior fiscal year end tax adjustments, if applicable.

Notes to Financial Statements (unaudited) – continued

Under the Regulated Investment Company Modernization Act of 2010 (the “Act”), net capital losses recognized for fund fiscal years beginning after August 31, 2011 may be carried forward indefinitely, and their character is retained as short-term and/or long-term losses (“post-enactment losses”). Previously, net capital losses were carried forward for eight years and treated as short-term losses (“pre-enactment losses”). As a transition rule, the Act requires that all post-enactment net capital losses be used before pre-enactment net capital losses.

As of August 31, 2017, the fund had capital loss carryforwards available to offset future realized gains as follows:


Pre-enactment losses which expire as follows:
8/31/18	$(268,624,124	)

Post-enactment losses which are characterized as follows:
Long-Term	$(115,723,546	)


	From net investment income
	Six months ended 2/28/18		Year ended 8/31/17
Class A		$7,325,996		$14,801,129
Class B		16,831		52,252
Class C		151,470		520,875
Class I		14,314,497		42,606,302
Class R1		10,568		17,739
Class R2		1,118,075		2,122,150
Class R3		992,523		1,806,343
Class R4		791,803		2,074,905
Class R6		82,520,374		58,847,369
Class 529A		130,984		178,025
Class 529B		1,445		7,154
Class 529C		25,907		61,177
Total		$107,400,473		$123,095,420

Notes to Financial Statements (unaudited) – continued

(3) Transactions with Affiliates


Up to $1 billion	0.90	%
In excess of $1 billion and up to $2 billion	0.80	%
In excess of $2 billion and up to $5 billion	0.70	%
In excess of $5 billion and up to $10 billion	0.60	%
In excess of $10 billion	0.55	%

MFS has agreed in writing to reduce its management fee by a specified amount if certain MFS mutual fund assets exceed thresholds agreed to by MFS and the fund’s Board of Trustees. For the six months ended February 28, 2018, this management fee reduction amounted to $339,005, which is included in the reduction of total expenses in the Statement of Operations. The management fee incurred for the six months ended February 28, 2018 was equivalent to an annual effective rate of 0.69% of the fund’s average daily net assets.

Distributor – MFS Fund Distributors, Inc. (MFD), a wholly-owned subsidiary of MFS, as distributor, received $39,454 and $4,222 for the six months ended February 28, 2018, as its portion of the initial sales charge on sales of Class A and Class 529A shares of the fund, respectively.

The Board of Trustees has adopted a distribution plan for certain share classes pursuant to Rule 12b-1 of the Investment Company Act of 1940.

Distribution Plan Fee Table:


	Distribution Fee Rate (d)		Service Fee Rate (d)		Total Distribution Plan (d)		Annual Effective Rate (e)		Distribution and Service Fee
Class A		—		0.25%		0.25%		0.25%		$873,716
Class B		0.75%		0.25%		1.00%		1.00%		30,539
Class C		0.75%		0.25%		1.00%		1.00%		242,203
Class R1		0.75%		0.25%		1.00%		1.00%		10,998
Class R2		0.25%		0.25%		0.50%		0.50%		357,875
Class R3		—		0.25%		0.25%		0.25%		115,340
Class 529A		—		0.25%		0.25%		0.23%		14,060
Class 529B		0.75%		0.25%		1.00%		1.00%		1,937
Class 529C		0.75%		0.25%		1.00%		0.99%		20,299
Total Distribution and Service Fees										$1,666,967

(d)	In accordance with the distribution plan for certain classes, the fund pays distribution and/or service fees equal to these annual percentage rates of each class’s average daily net assets. The

Notes to Financial Statements (unaudited) – continued

distribution and service fee rates disclosed by class represent the current rates in effect at the end of the reporting period. Any rate changes, if applicable, are detailed below.

(e)

The annual effective rates represent actual fees incurred under the distribution plan for the six months ended February 28, 2018 based on each class’s average daily net assets. MFD has voluntarily agreed to rebate a portion of each class’s 0.25% service fee attributable to accounts for which MFD retains the 0.25% service fee except for accounts attributable to MFS or its affiliates’ seed money. For the six months ended February 28, 2018, this rebate amounted to $5,155, $116, $159, $1, $1,084, and $163 for Class A, Class B, Class C, Class R2, Class 529A, and Class 529C, respectively, and is included in the reduction of total expenses in the Statement of Operations.


	Amount
Class A		$1,011
Class B		2,264
Class C		805
Class 529B		—
Class 529C		131

The fund has entered into and may from time to time enter into contracts with program managers and other parties which administer the tuition programs through which an investment in the fund’s 529 share classes is made. For the period from September 1, 2017 through December 10, 2017, the fund had entered into an agreement with MFD pursuant to which MFD received an annual fee of up to 0.10% of the average daily net assets attributable to each 529 share class. MFD had agreed to waive a portion of this fee in an amount equal to 0.05% of the average daily net assets for each 529 share class. This waiver agreement terminated on December 10, 2017. For the period from September 1, 2017 through December 10, 2017, this waiver amounted to $2,120 and is included in the reduction of total expenses in the Statement of Operations. Effective December 11, 2017, the fund has entered into an agreement with MFD pursuant to which MFD receives an annual fee of up to 0.05% of the average daily net assets attributable to each 529 share class. The program manager fee incurred for the six months ended February 28, 2018 was equivalent to an annual effective rate of 0.05% of the average daily net assets attributable to each 529 share class. The services provided by MFD, or a third party with which MFD contracts, include recordkeeping and tax reporting and account services, as well as services designed to

Notes to Financial Statements (unaudited) – continued

maintain the program’s compliance with the Internal Revenue Code and other regulatory requirements. Program manager fees and waivers for the six months ended February 28, 2018, were as follows:


	Fee		Waiver
Class 529A		$4,323		$1,511
Class 529B		151		54
Class 529C		1,569		555
Total Program Manager Fees and Waivers		$6,043		$2,120

Shareholder Servicing Agent – MFS Service Center, Inc. (MFSC), a wholly-owned subsidiary of MFS, receives a fee from the fund for its services as shareholder servicing agent calculated as a percentage of the average daily net assets of the fund as determined periodically under the supervision of the fund’s Board of Trustees. For the six months ended February 28, 2018, the fee was $111,596, which equated to 0.0028% annually of the fund’s average daily net assets. MFSC also receives payment from the fund for out-of-pocket expenses, sub-accounting and other shareholder servicing costs which may be paid to affiliated and unaffiliated service providers. Class R6 shares do not incur sub-accounting fees. For the six months ended February 28, 2018, these out-of-pocket expenses, sub-accounting and other shareholder servicing costs amounted to $1,200,793.

Prior to December 31, 2001, the fund had an unfunded defined benefit plan (“DB plan”) for independent Trustees. As of December 31, 2001, the Board took action to terminate the DB plan with respect to then-current and any future independent Trustees, such that the DB plan covers only certain of those former independent Trustees who retired on or before December 31, 2001. The DB plan resulted in a pension expense of $131 and is included in “Independent Trustees’ compensation” in the Statement of Operations for the six months ended February 28, 2018. The liability for deferred retirement benefits payable to certain independent Trustees under the DB plan amounted to $567 at February 28, 2018, and is included in “Payable for independent Trustees’ compensation” in the Statement of Assets and Liabilities.

Other – This fund and certain other funds managed by MFS (the funds) have entered into a service agreement (the ISO Agreement) which provides for payment of fees

Notes to Financial Statements (unaudited) – continued

solely by the funds to Tarantino LLC in return for the provision of services of an Independent Senior Officer (ISO) for the funds. Frank L. Tarantino serves as the ISO and is an officer of the funds and the sole member of Tarantino LLC. The funds can terminate the ISO Agreement with Tarantino LLC at any time under the terms of the ISO Agreement. For the six months ended February 28, 2018, the fee paid by the fund under this agreement was $6,247 and is included in “Miscellaneous” expense in the Statement of Operations. MFS has agreed to bear all expenses associated with office space, other administrative support, and supplies provided to the ISO.

The fund is permitted to engage in purchase and sale transactions with funds and accounts for which MFS serves as investment adviser or sub-adviser (“cross-trades”) pursuant to a policy adopted by the Board of Trustees. This policy has been designed to ensure that cross-trades conducted by the fund comply with Rule 17a-7 under the Investment Company Act of 1940. During the six months ended February 28, 2018, the fund engaged in purchase and sale transactions pursuant to this policy, which amounted to $9,210,045 and $563,431, respectively. The sales transactions resulted in net realized gains (losses) of $(96,715).

(4) Portfolio Securities

For the six months ended February 28, 2018, purchases and sales of investments, other than short-term obligations, aggregated $1,271,806,289 and $927,976,873, respectively.

(5) Shares of Beneficial Interest

The fund’s Declaration of Trust permits the Trustees to issue an unlimited number of full and fractional shares of beneficial interest. Transactions in fund shares were as follows:


	Six months ended 2/28/18				Year ended 8/31/17
	Shares		Amount		Shares		Amount
Shares sold
Class A		4,457,197		$84,074,507		8,582,981		$138,223,182
Class B		8,805		161,085		34,564		554,571
Class C		124,297		2,218,454		253,541		3,952,051
Class I		7,082,022		139,881,624		42,721,875		720,116,950
Class R1		11,403		207,740		16,068		246,173
Class R2		2,404,522		44,734,032		1,287,477		20,166,349
Class R3		397,313		7,558,201		1,343,734		21,647,695
Class R4		318,546		6,093,929		1,102,171		17,981,607
Class R6		57,414,457		1,100,370,591		132,775,681		2,295,191,131
Class 529A		69,724		1,325,412		82,941		1,344,959
Class 529B		710		12,586		1,775		27,433
Class 529C		16,035		277,420		34,844		515,747
		72,305,031		$1,386,915,581		188,237,652		$3,219,967,848

Notes to Financial Statements (unaudited) – continued


	Six months ended 2/28/18						Year ended 8/31/17
	Shares			Amount			Shares			Amount
Shares issued to shareholders in reinvestment of distributions
Class A		278,109			$5,278,502			753,070			$11,612,342
Class B		776			14,248			2,923			43,611
Class C		6,372			113,995			22,145			321,994
Class I		370,149			7,262,325			2,119,423			33,762,412
Class R1		597			10,519			1,232			17,670
Class R2		58,080			1,066,343			135,578			2,022,831
Class R3		52,822			992,523			118,371			1,806,343
Class R4		41,572			789,876			134,339			2,072,857
Class R6		4,368,877			82,397,020			3,829,739			58,709,900
Class 529A		7,033			130,963			11,741			177,872
Class 529B		82			1,445			499			7,154
Class 529C		1,499			25,907			4,342			61,177
		5,185,968			$98,083,666			7,133,402			$110,616,163

Shares reacquired
Class A		(6,722,857	)		$(126,973,268	)		(32,516,368	)		$(523,334,043	)
Class B		(57,690	)		(1,065,881	)		(205,001	)		(3,230,732	)
Class C		(398,858	)		(7,158,233	)		(1,608,153	)		(25,050,058	)
Class I		(28,732,775	)		(574,905,414	)		(119,850,510	)		(2,144,302,000	)
Class R1		(14,784	)		(263,947	)		(58,236	)		(871,875	)
Class R2		(1,414,017	)		(26,258,240	)		(3,781,953	)		(59,658,034	)
Class R3		(941,041	)		(17,940,458	)		(4,467,029	)		(72,551,216	)
Class R4		(537,190	)		(10,198,636	)		(7,076,802	)		(118,677,345	)
Class R6		(15,129,013	)		(290,614,329	)		(22,885,746	)		(378,877,194	)
Class 529A		(38,685	)		(731,168	)		(91,229	)		(1,471,469	)
Class 529B		(2,666	)		(47,215	)		(8,674	)		(132,298	)
Class 529C		(17,981	)		(319,072	)		(32,507	)		(477,283	)
		(54,007,557	)		$(1,056,475,861	)		(192,582,208	)		$(3,328,633,547	)

Net change
Class A		(1,987,551	)		$(37,620,259	)		(23,180,317	)		$(373,498,519	)
Class B		(48,109	)		(890,548	)		(167,514	)		(2,632,550	)
Class C		(268,189	)		(4,825,784	)		(1,332,467	)		(20,776,013	)
Class I		(21,280,604	)		(427,761,465	)		(75,009,212	)		(1,390,422,638	)
Class R1		(2,784	)		(45,688	)		(40,936	)		(608,032	)
Class R2		1,048,585			19,542,135			(2,358,898	)		(37,468,854	)
Class R3		(490,906	)		(9,389,734	)		(3,004,924	)		(49,097,178	)
Class R4		(177,072	)		(3,314,831	)		(5,840,292	)		(98,622,881	)
Class R6		46,654,321			892,153,282			113,719,674			1,975,023,837
Class 529A		38,072			725,207			3,453			51,362
Class 529B		(1,874	)		(33,184	)		(6,400	)		(97,711	)
Class 529C		(447	)		(15,745	)		6,679			99,641
		23,483,442			$428,523,386			2,788,846			$1,950,464

Notes to Financial Statements (unaudited) – continued

Class T shares were not publicly available for sale during the period. Please see the fund’s prospectus for details.

The fund is one of several mutual funds in which certain MFS funds may invest. The MFS funds do not invest in the underlying funds for the purpose of exercising management or control. At the end of the period, the MFS international Diversification Fund, the MFS Growth Allocation Fund, the MFS Moderate Allocation Fund, the MFS Aggressive Growth Allocation Fund, and the MFS Conservative Allocation Fund were the owners of record of approximately 41%, 4%, 4%, 2%, and 1%, respectively, of the value of outstanding voting shares of the fund. In addition, the MFS Lifetime 2020 Fund, the MFS Lifetime 2025 Fund, the MFS Lifetime 2030 Fund, the MFS Lifetime 2035 Fund, the MFS Lifetime 2040 Fund, the MFS Lifetime 2045 Fund, the MFS Lifetime 2050 Fund, the MFS Lifetime 2055 Fund, the MFS Lifetime 2060 Fund, and the MFS Lifetime Income Fund were each the owners of record of less than 1% of the value of outstanding voting shares of the fund.

(6) Line of Credit

The fund and certain other funds managed by MFS participate in a $1.25 billion unsecured committed line of credit, subject to a $1 billion sublimit, provided by a syndication of banks under a credit agreement. Borrowings may be made for temporary financing needs. Interest is charged to each fund, based on its borrowings, generally at a rate equal to the higher of the Overnight Federal Reserve funds rate or daily one month LIBOR plus an agreed upon spread. A commitment fee, based on the average daily, unused portion of the committed line of credit, is allocated among the participating funds at the end of each calendar quarter. In addition, the fund and other funds managed by MFS have established unsecured uncommitted borrowing arrangements with certain banks for temporary financing needs. Interest is charged to each fund, based on its borrowings, at a rate equal to the Overnight Federal Reserve funds rate plus an agreed upon spread. For the six months ended February 28, 2018, the fund’s commitment fee and interest expense were $23,862 and $0, respectively, and are included in “Miscellaneous” expense in the Statement of Operations.

(7) Investments in Affiliated Issuers


Affiliated Issuers			Beginning Shares/Par Amount			Acquisitions Shares/Par Amount		Dispositions Shares/Par Amount			Ending Shares/Par Amount
MFS Institutional Money Market Portfolio				97,839,200			529,016,483		(516,298,559	)		110,557,124

Affiliated Issuers	Realized Gain (Loss)		Change in Unrealized Appreciation (Depreciation)			Capital Gain Distributions		Dividend Income			Ending Value
MFS Institutional Money Market Portfolio		$2,771		$(2,578	)		$—		$568,623			$110,546,068

PROXY VOTING POLICIES AND INFORMATION

QUARTERLY PORTFOLIO DISCLOSURE

Public Reference Room

Securities and Exchange Commission

100 F Street, NE, Room 1580

Washington, D.C. 20549

FURTHER INFORMATION

INFORMATION ABOUT FUND CONTRACTS AND LEGAL CLAIMS

PROVISION OF FINANCIAL REPORTS AND SUMMARY PROSPECTUSES

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CONTACT

WEB SITE

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MAILING ADDRESS

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Semiannual Report

February 28, 2018

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MFS® Technology Fund

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SCT-SEM

MFS® Technology Fund

CONTENTS


Letter from the Executive Chairman			1
Portfolio composition			2
Expense table			3
Portfolio of investments			5
Statement of assets and liabilities			9
Statement of operations			11
Statements of changes in net assets			12
Financial highlights			13
Notes to financial statements			22
Proxy voting policies and information			33
Quarterly portfolio disclosure			33
Further information			33
Information about fund contracts and legal claims			34
Provision of financial reports and summary prospectuses			34
Contact information back cover

The report is prepared for the general information of shareholders.

It is authorized for distribution to prospective investors only when preceded or accompanied by a current prospectus.

NOT FDIC INSURED • MAY LOSE VALUE • NO BANK GUARANTEE

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LETTER FROM THE EXECUTIVE CHAIRMAN

Dear Shareholders:

Rising bond yields have led to a measurable uptick in market volatility — a departure from the low-volatility environment that prevailed for much of 2017. In spite of this,

U.S. protectionism is also a growing concern, as investors fear that trade friction could disrupt the synchronized uptick in global growth.

Respectfully,

LOGO

Robert J. Manning

Executive Chairman

MFS Investment Management

April 13, 2018

The opinions expressed in this letter are subject to change and may not be relied upon for investment advice. No forecasts can be guaranteed.

PORTFOLIO COMPOSITION

Portfolio structure

LOGO


Top ten holdings
Alphabet, Inc., “A”			9.7%
Facebook, Inc., “A”			8.4%
Amazon.com, Inc.			6.5%
Microsoft Corp.			4.2%
Salesforce.com, Inc.			4.1%
DXC Technology Co.			4.0%
Adobe Systems, Inc.			4.0%
Visa, Inc., “A”			3.6%
Mastercard, Inc., “A”			2.8%
Broadcom Corp.			2.8%


Top five industries
Internet			21.7%
Business Services			16.7%
Computer Software			16.5%
Computer Software-Systems			7.5%
Electronics (s)			7.1%

(s)	Includes securities sold short.

Percentages are based on net assets as of February 28, 2018.

The portfolio is actively managed and current holdings may be different.

EXPENSE TABLE

Fund expenses borne by the shareholders during the period, September 1, 2017 through February 28, 2018

The example is based on an investment of $1,000 invested at the beginning of the period and held for the entire period September 1, 2017 through February 28, 2018.

Actual Expenses

Hypothetical Example for Comparison Purposes

Expense Table – continued


Share Class		Annualized Expense Ratio	Beginning Account Value 9/01/17	Ending Account Value 2/28/18	Expenses Paid During Period (p) 9/01/17-2/28/18
A	Actual	1.18%	$1,000.00	$1,165.56		$6.34
A	Hypothetical (h)	1.18%	$1,000.00	$1,018.94		$5.91
B	Actual	1.93%	$1,000.00	$1,161.10		$10.34
B	Hypothetical (h)	1.93%	$1,000.00	$1,015.22		$9.64
C	Actual	1.93%	$1,000.00	$1,161.10		$10.34
C	Hypothetical (h)	1.93%	$1,000.00	$1,015.22		$9.64
I	Actual	0.93%	$1,000.00	$1,166.91		$5.00
I	Hypothetical (h)	0.93%	$1,000.00	$1,020.18		$4.66
R1	Actual	1.93%	$1,000.00	$1,161.08		$10.34
R1	Hypothetical (h)	1.93%	$1,000.00	$1,015.22		$9.64
R2	Actual	1.43%	$1,000.00	$1,164.02		$7.67
R2	Hypothetical (h)	1.43%	$1,000.00	$1,017.70		$7.15
R3	Actual	1.18%	$1,000.00	$1,165.31		$6.34
R3	Hypothetical (h)	1.18%	$1,000.00	$1,018.94		$5.91
R4	Actual	0.93%	$1,000.00	$1,166.87		$5.00
R4	Hypothetical (h)	0.93%	$1,000.00	$1,020.18		$4.66
R6	Actual	0.84%	$1,000.00	$1,167.40		$4.51
R6	Hypothetical (h)	0.84%	$1,000.00	$1,020.63		$4.21

(h)	5% class return per year before expenses.

(p)

Notes to Expense Table

Expense ratios include 0.01% of investment related expenses from short sales (See Note 2 of the Notes to Financial Statements).

Each class with a Rule 12b-1 service fee is subject to a rebate of a portion of such fee. Such rebates are included in the expense ratios above. For Class A shares, this rebate reduced the expense ratio above by 0.01%. See Note 3 in the Notes to Financial Statements for additional information.

PORTFOLIO OF INVESTMENTS

2/28/18 (unaudited)

The Portfolio of Investments is a complete list of all securities owned by your fund. It is categorized by broad-based asset classes.


Common Stocks - 99.1%
Issuer	Shares/Par		Value ($)
Aerospace - 3.5%
CACI International, Inc., “A” (a)		44,769	$	6,672,819
FLIR Systems, Inc.		97,185		4,771,784
Harris Corp.		56,825		8,873,224
Leidos Holdings, Inc.		93,920		5,946,075
Northrop Grumman Corp.		24,034		8,412,861

			$	34,676,763
Broadcasting - 2.6%
Netflix, Inc. (a)		90,910	$	26,489,356

Brokerage & Asset Managers - 1.6%
Intercontinental Exchange, Inc.		72,465	$	5,295,742
NASDAQ, Inc.		128,242		10,355,542

			$	15,651,284
Business Services - 16.6%
Cognizant Technology Solutions Corp., “A”		261,583	$	21,455,038
DXC Technology Co.		393,789		40,379,124
Fidelity National Information Services, Inc.		167,791		16,305,929
First Data Corp. (a)		344,063		5,374,264
Fiserv, Inc. (a)		81,122		11,632,084
FleetCor Technologies, Inc. (a)		42,702		8,537,411
Global Payments, Inc.		145,306		16,476,247
Grand Canyon Education, Inc. (a)		72,619		7,127,555
PagSeguro Digital Ltd. (a)		157,143		5,066,290
PayPal Holdings, Inc. (a)		227,363		18,054,896
Total System Services, Inc.		79,602		7,000,996
TransUnion (a)		58,222		3,322,729
Verisk Analytics, Inc., “A” (a)		27,643		2,824,838
Zendesk, Inc. (a)		74,000		3,195,320

			$	166,752,721
Cable TV - 1.4%
Altice USA, Inc. (a)(l)		272,042	$	4,951,164
Comcast Corp., “A”		240,443		8,706,441

			$	13,657,605
Computer Software - 16.5%
Adobe Systems, Inc. (a)		192,742	$	40,308,134
Autodesk, Inc. (a)		84,697		9,949,357

Portfolio of Investments (unaudited) – continued


Issuer	Shares/Par		Value ($)
Common Stocks - continued
Computer Software - continued
Cadence Design Systems, Inc. (a)		105,507	$	4,090,506
Microsoft Corp.		447,950		42,004,272
MuleSoft, Inc., “A” (a)		188,238		5,812,789
PTC, Inc. (a)		104,772		7,727,983
Red Hat, Inc. (a)		60,339		8,893,969
RingCentral, Inc. (a)		88,411		5,538,949
Salesforce.com, Inc. (a)		352,843		41,017,999

			$	165,343,958
Computer Software - Systems - 7.5%
Apple, Inc.		136,433	$	24,301,446
Constellation Software, Inc.		13,940		9,023,087
EPAM Systems, Inc. (a)		67,496		7,635,148
New Relic, Inc. (a)		82,389		5,913,882
Presidio, Inc. (a)		732,705		10,712,147
Rapid7, Inc. (a)		193,939		5,121,929
ServiceNow, Inc. (a)		60,324		9,712,767
Switch, Inc.		179,683		2,481,422

			$	74,901,828
Consumer Services - 0.5%
Bookings Holdings, Inc. (a)		2,521	$	5,127,815

Electrical Equipment - 2.2%
Amphenol Corp., “A”		112,327	$	10,265,564
Littlefuse, Inc.		7,116		1,476,570
TE Connectivity Ltd.		100,831		10,394,668

			$	22,136,802
Electronics - 7.6%
Applied Materials, Inc.		280,871	$	16,175,361
Broadcom Corp.		112,148		27,639,996
Microchip Technology, Inc.		244,009		21,699,720
Microsemi Corp. (a)		37,423		2,428,753
NVIDIA Corp.		8,957		2,167,594
NXP Semiconductors N.V. (a)		4,037		503,252
Silicon Laboratories, Inc. (a)		55,062		5,148,297

			$	75,762,973
Internet - 21.6%
Alibaba Group Holding Ltd., ADR (a)		122,723	$	22,843,659
Alphabet, Inc., “A” (a)(s)		87,512		96,606,247
Facebook, Inc., “A” (a)(s)		473,211		84,382,986
Godaddy, Inc. (a)		140,423		8,398,700

Portfolio of Investments (unaudited) – continued


Issuer	Shares/Par			Value ($)
Common Stocks - continued
Internet - continued
Match Group, Inc. (a)(l)		113,469		$	4,544,433

				$	216,776,025
Leisure & Toys - 3.5%
Activision Blizzard, Inc.		179,903		$	13,156,306
Electronic Arts, Inc. (a)		114,282			14,136,684
Take-Two Interactive Software, Inc. (a)		72,123			8,068,400

				$	35,361,390
Network & Telecom - 0.5%
Qualcomm, Inc.		76,355		$	4,963,075

Other Banks & Diversified Financials - 6.4%
Mastercard, Inc., “A”		161,418		$	28,370,828
Visa, Inc., “A”		291,915			35,888,030

				$	64,258,858
Printing & Publishing - 0.6%
IHS Markit Ltd. (a)		122,493		$	5,763,296

Specialty Stores - 6.5%
Amazon.com, Inc. (a)(s)		42,769		$	64,685,974
Total Common Stocks (Identified Cost, $564,703,090)				$	992,309,723

Investment Companies (h) - 1.0%
Money Market Funds - 1.0%
MFS Institutional Money Market Portfolio, 1.52% (v) (Identified Cost, $9,617,361)		9,618,675		$	9,617,713

Collateral for Securities Loaned - 0.3%
State Street Navigator Securities Lending Government Money Market Portfolio, 1.37% (j) (Identified Cost, $2,647,798)		2,647,798		$	2,647,798

Securities Sold Short - (0.4)%
Electronics - (0.4)%
Qorvo, Inc. (Proceeds Received, $3,641,923)		(55,079	)	$	(4,445,426	)

Other Assets, Less Liabilities - 0.0%					789,395
Net Assets - 100.0%				$	1,000,919,203

(a)	Non-income producing security.

(h)

Portfolio of Investments (unaudited) – continued

(j)	The rate quoted is the annualized seven-day yield of the fund at period end.

(l)	A portion of this security is on loan.

(s)	Security or a portion of the security was pledged to cover collateral requirements for securities sold short and/or certain derivative transactions.

(v)	Affiliated issuer that is available only to investment companies managed by MFS. The rate quoted for the MFS Institutional Money Market Portfolio is the annualized seven-day yield of the fund at period end.

The following abbreviations are used in this report and are defined:

ADR

American Depositary Receipt

At February 28, 2018, the fund had cash collateral of $3,382,480 and other liquid securities with an aggregate value of $5,584,012 to cover any collateral or margin obligations for securities sold short. Cash collateral is comprised of “Deposits with Brokers” on the Statement of Assets and Liabilities.

See Notes to Financial Statements

Financial Statements

STATEMENT OF ASSETS AND LIABILITIES

At 2/28/18 (unaudited)

This statement represents your fund’s balance sheet, which details the assets and liabilities comprising the total value of the fund.


Assets
Investments in unaffiliated issuers, at value, including $3,906,858 of securities on loan (identified cost, $567,350,888)	$994,957,521
Investments in affiliated issuers, at value (identified cost, $9,617,361)	9,617,713
Deposits with brokers for securities sold short	3,382,480
Receivables for
Investments sold	6,520,727
Fund shares sold	3,957,202
Interest and dividends	482,759
Other assets	3,750
Total assets	$1,018,922,152
Liabilities
Payables for
Securities sold short, at value (proceeds received, $3,641,923)	$4,445,426
Investments purchased	9,700,379
Fund shares reacquired	919,190
Collateral for securities loaned, at value (c)	2,647,798
Payable to affiliates
Investment adviser	47,452
Shareholder servicing costs	219,937
Distribution and service fees	15,425
Payable for independent Trustees’ compensation	611
Accrued expenses and other liabilities	6,731
Total liabilities	$18,002,949
Net assets	$1,000,919,203
Net assets consist of
Paid-in capital	$550,033,372
Unrealized appreciation (depreciation)	426,803,482
Accumulated net realized gain (loss)	27,073,200
Accumulated net investment loss	(2,990,851	)
Net assets	$1,000,919,203
Shares of beneficial interest outstanding	25,101,164

(c)	Non-cash collateral is not included.

Statement of Assets and Liabilities (unaudited) – continued


	Net assets		Shares outstanding		Net asset value per share (a)
Class A		$404,419,732		10,094,090		$40.07
Class B		38,417,705		1,102,559		34.84
Class C		120,184,172		3,456,322		34.77
Class I		216,771,042		5,074,648		42.72
Class R1		4,990,966		143,818		34.70
Class R2		26,214,659		685,068		38.27
Class R3		65,021,032		1,623,571		40.05
Class R4		17,909,803		430,411		41.61
Class R6		106,990,092		2,490,677		42.96

(a)

Maximum offering price per share was equal to the net asset value per share for all share classes, except for Class A, for which the maximum offering price per share was $42.51 [100 / 94.25 x $40.07]. On sales of $50,000 or more, the maximum offering price of Class A shares is reduced. A contingent deferred sales charge may be imposed on redemptions of Class A, Class B, and Class C shares. Redemption price per share was equal to the net asset value per share for Classes I, R1, R2, R3, R4, and R6. Net asset value per share is calculated using actual net assets and shares outstanding rather than amounts that have been rounded for presentation purposes.

See Notes to Financial Statements

Financial Statements

STATEMENT OF OPERATIONS

Six months ended 2/28/18 (unaudited)

This statement describes how much your fund earned in investment income and accrued in expenses. It also describes any gains and/or losses generated by fund operations.


Net investment income (loss)
Income
Dividends	$2,452,541
Dividends from affiliated issuers	92,742
Interest	26,672
Income on securities loaned	16,604
Foreign taxes withheld	(5,185	)
Total investment income	$2,583,374
Expenses
Management fee	$3,440,453
Distribution and service fees	1,344,810
Shareholder servicing costs	503,775
Administrative services fee	73,722
Independent Trustees’ compensation	8,070
Custodian fee	23,324
Shareholder communications	32,269
Audit and tax fees	29,029
Legal fees	4,246
Dividend and interest expense on securities sold short	66,394
Miscellaneous	96,659
Total expenses	$5,622,751
Reduction of expenses by investment adviser and distributor	(49,153	)
Net expenses	$5,573,598
Net investment income (loss)	$(2,990,224	)
Realized and unrealized gain (loss)
Realized gain (loss) (identified cost basis)
Unaffiliated issuers	$33,992,369
Affiliated issuers	(2,455	)
Securities sold short	(697,842	)
Foreign currency	532
Net realized gain (loss)	$33,292,604
Change in unrealized appreciation (depreciation)
Unaffiliated issuers	$111,766,327
Affiliated issuers	39
Securities sold short	(844,064	)
Net unrealized gain (loss)	$110,922,302
Net realized and unrealized gain (loss)	$144,214,906
Change in net assets from operations	$141,224,682

See Notes to Financial Statements

Financial Statements

STATEMENTS OF CHANGES IN NET ASSETS

These statements describe the increases and/or decreases in net assets resulting from operations, any distributions, and any shareholder transactions.


Change in net assets	Six months ended 2/28/18 (unaudited)			Year ended 8/31/17
From operations
Net investment income (loss)		$(2,990,224	)		$(4,957,880	)
Net realized gain (loss)		33,292,604			46,016,002
Net unrealized gain (loss)		110,922,302			147,169,413
Change in net assets from operations		$141,224,682			$188,227,535
Distributions declared to shareholders
From net realized gain		$(34,022,224	)		$(12,086,828	)
Change in net assets from fund share transactions		$32,633,929			$86,447,267
Total change in net assets		$139,836,387			$262,587,974
Net assets
At beginning of period		861,082,816			598,494,842
At end of period (including accumulated net investment loss of $2,990,851 and $627, respectively)		$1,000,919,203			$861,082,816

See Notes to Financial Statements

Financial Statements

FINANCIAL HIGHLIGHTS


	Six months ended 2/28/18			Year ended
Class A	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14			8/31/13
	(unaudited)

Net asset value, beginning of period		$35.67			$28.27			$24.62			$24.47			$19.41			$16.80
Income (loss) from investment operations
Net investment income (loss) (d)		$(0.12	)		$(0.19	)(c)		$(0.12	)		$(0.15	)		$(0.13	)		$(0.12	)
Net realized and unrealized gain (loss)		5.89			8.13			4.76			1.15			5.19			2.73
Total from investment operations		$5.77			$7.94			$4.64			$1.00			$5.06			$2.61
Less distributions declared to shareholders
From net realized gain		$(1.37	)		$(0.54	)		$(0.99	)		$(0.85	)		$—			$—
Net asset value, end of period (x)		$40.07			$35.67			$28.27			$24.62			$24.47			$19.41
Total return (%) (r)(s)(t)(x)		16.56	(n)		28.58	(c)		19.20			4.18			26.07			15.54
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.19	(a)		1.24	(c)		1.27			1.30			1.33			1.55
Expenses after expense reductions (f)		1.18	(a)		1.23	(c)		1.26			1.29			1.32			1.54
Net investment income (loss)		(0.62	)(a)		(0.63	)(c)		(0.48	)		(0.60	)		(0.58	)		(0.70	)
Portfolio turnover		18	(n)		43			30			43			38			54
Net assets at end of period (000 omitted)		$404,420			$359,698			$320,898			$199,313			$171,020			$141,147
Supplemental Ratios (%):
Ratio of expenses to average net assets after expense reductions excluding short sale expenses (f)		1.16	(a)		1.19	(c)		1.24			1.27			1.28			1.36

See Notes to Financial Statements

Financial Highlights – continued


	Six months ended 2/28/18			Year ended
Class B	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14			8/31/13
	(unaudited)

Net asset value, beginning of period		$31.31			$25.06			$22.09			$22.20			$17.75			$15.48
Income (loss) from investment operations
Net investment income (loss) (d)		$(0.22	)		$(0.38	)(c)		$(0.28	)		$(0.30	)		$(0.27	)		$(0.23	)
Net realized and unrealized gain (loss)		5.12			7.17			4.24			1.04			4.72			2.50
Total from investment operations		$4.90			$6.79			$3.96			$0.74			$4.45			$2.27
Less distributions declared to shareholders
From net realized gain		$(1.37	)		$(0.54	)		$(0.99	)		$(0.85	)		$—			$—
Net asset value, end of period (x)		$34.84			$31.31			$25.06			$22.09			$22.20			$17.75
Total return (%) (r)(s)(t)(x)		16.07	(n)		27.64	(c)		18.29			3.41			25.07			14.66
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.94	(a)		1.99	(c)		2.02			2.05			2.08			2.30
Expenses after expense reductions (f)		1.93	(a)		1.98	(c)		2.01			2.04			2.07			2.29
Net investment income (loss)		(1.37	)(a)		(1.38	)(c)		(1.22	)		(1.35	)		(1.34	)		(1.44	)
Portfolio turnover		18	(n)		43			30			43			38			54
Net assets at end of period (000 omitted)		$38,418			$34,396			$25,990			$18,791			$16,190			$13,009
Supplemental Ratios (%):
Ratio of expenses to average net assets after expense reductions excluding short sale expenses (f)		1.92	(a)		1.94	(c)		1.99			2.02			2.03			2.12

See Notes to Financial Statements

Financial Highlights – continued


	Six months ended 2/28/18			Year ended
Class C	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14			8/31/13
	(unaudited)

Net asset value, beginning of period		$31.24			$25.01			$22.05			$22.16			$17.71			$15.45
Income (loss) from investment operations
Net investment income (loss) (d)		$(0.22	)		$(0.38	)(c)		$(0.28	)		$(0.30	)		$(0.28	)		$(0.24	)
Net realized and unrealized gain (loss)		5.12			7.15			4.23			1.04			4.73			2.50
Total from investment operations		$4.90			$6.77			$3.95			$0.74			$4.45			$2.26
Less distributions declared to shareholders
From net realized gain		$(1.37	)		$(0.54	)		$(0.99	)		$(0.85	)		$—			$—
Net asset value, end of period (x)		$34.77			$31.24			$25.01			$22.05			$22.16			$17.71
Total return (%) (r)(s)(t)(x)		16.11	(n)		27.62	(c)		18.28			3.42			25.13			14.63
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.94	(a)		1.99	(c)		2.02			2.05			2.07			2.30
Expenses after expense reductions (f)		1.93	(a)		1.98	(c)		2.01			2.04			2.07			2.30
Net investment income (loss)		(1.37	)(a)		(1.38	)(c)		(1.23	)		(1.35	)		(1.34	)		(1.45	)
Portfolio turnover		18	(n)		43			30			43			38			54
Net assets at end of period (000 omitted)		$120,184			$101,656			$73,071			$43,037			$35,998			$25,026
Supplemental Ratios (%):
Ratio of expenses to average net assets after expense reductions excluding short sale expenses (f)		1.92	(a)		1.94	(c)		2.00			2.02			2.03			2.12

See Notes to Financial Statements

Financial Highlights – continued


	Six months ended 2/28/18			Year ended
Class I	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14			8/31/13
	(unaudited)

Net asset value, beginning of period		$37.90			$29.93			$25.96			$25.69			$20.33			$17.56
Income (loss) from investment operations
Net investment income (loss) (d)		$(0.07	)		$(0.13	)(c)		$(0.07	)		$(0.09	)		$(0.08	)		$(0.08	)
Net realized and unrealized gain (loss)		6.26			8.64			5.03			1.21			5.44			2.85
Total from investment operations		$6.19			$8.51			$4.96			$1.12			$5.36			$2.77
Less distributions declared to shareholders
From net realized gain		$(1.37	)		$(0.54	)		$(0.99	)		$(0.85	)		$—			$—
Net asset value, end of period (x)		$42.72			$37.90			$29.93			$25.96			$25.69			$20.33
Total return (%) (r)(s)(t)(x)		16.69	(n)		28.91	(c)		19.45			4.45			26.36			15.77
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		0.94	(a)		0.99	(c)		1.02			1.05			1.08			1.30
Expenses after expense reductions (f)		0.93	(a)		0.98	(c)		1.01			1.04			1.07			1.30
Net investment income (loss)		(0.37	)(a)		(0.39	)(c)		(0.24	)		(0.35	)		(0.35	)		(0.45	)
Portfolio turnover		18	(n)		43			30			43			38			54
Net assets at end of period (000 omitted)		$216,771			$174,275			$96,700			$56,619			$40,359			$30,615
Supplemental Ratios (%):
Ratio of expenses to average net assets after expense reductions excluding short sale expenses (f)		0.92	(a)		0.95	(c)		1.00			1.02			1.04			1.12

See Notes to Financial Statements

Financial Highlights – continued


	Six months ended 2/28/18			Year ended
Class R1	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14			8/31/13
	(unaudited)

Net asset value, beginning of period		$31.18			$24.96			$22.01			$22.12			$17.68			$15.42
Income (loss) from investment operations
Net investment income (loss) (d)		$(0.22	)		$(0.38	)(c)		$(0.28	)		$(0.30	)		$(0.27	)		$(0.23	)
Net realized and unrealized gain (loss)		5.11			7.14			4.22			1.04			4.71			2.49
Total from investment operations		$4.89			$6.76			$3.94			$0.74			$4.44			$2.26
Less distributions declared to shareholders
From net realized gain		$(1.37	)		$(0.54	)		$(0.99	)		$(0.85	)		$—			$—
Net asset value, end of period (x)		$34.70			$31.18			$24.96			$22.01			$22.12			$17.68
Total return (%) (r)(s)(t)(x)		16.11	(n)		27.63	(c)		18.27			3.43			25.11			14.66
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.94	(a)		1.99	(c)		2.02			2.05			2.08			2.30
Expenses after expense reductions (f)		1.93	(a)		1.98	(c)		2.01			2.04			2.07			2.30
Net investment income (loss)		(1.37	)(a)		(1.38	)(c)		(1.22	)		(1.36	)		(1.34	)		(1.45	)
Portfolio turnover		18	(n)		43			30			43			38			54
Net assets at end of period (000 omitted)		$4,991			$4,256			$3,073			$2,516			$2,033			$1,542
Supplemental Ratios (%):
Ratio of expenses to average net assets after expense reductions excluding short sale expenses (f)		1.92	(a)		1.95	(c)		1.99			2.02			2.04			2.12

See Notes to Financial Statements

Financial Highlights – continued


	Six months ended 2/28/18			Year ended
Class R2	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14			8/31/13
	(unaudited)

Net asset value, beginning of period		$34.17			$27.17			$23.76			$23.70			$18.85			$16.36
Income (loss) from investment operations
Net investment income (loss) (d)		$(0.16	)		$(0.26	)(c)		$(0.18	)		$(0.20	)		$(0.18	)		$(0.16	)
Net realized and unrealized gain (loss)		5.63			7.80			4.58			1.11			5.03			2.65
Total from investment operations		$5.47			$7.54			$4.40			$0.91			$4.85			$2.49
Less distributions declared to shareholders
From net realized gain		$(1.37	)		$(0.54	)		$(0.99	)		$(0.85	)		$—			$—
Net asset value, end of period (x)		$38.27			$34.17			$27.17			$23.76			$23.70			$18.85
Total return (%) (r)(s)(t)(x)		16.40	(n)		28.27	(c)		18.88			3.93			25.73			15.22
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.44	(a)		1.49	(c)		1.52			1.55			1.58			1.79
Expenses after expense reductions (f)		1.43	(a)		1.49	(c)		1.51			1.54			1.58			1.79
Net investment income (loss)		(0.87	)(a)		(0.89	)(c)		(0.72	)		(0.84	)		(0.83	)		(0.94	)
Portfolio turnover		18	(n)		43			30			43			38			54
Net assets at end of period (000 omitted)		$26,215			$23,625			$17,031			$14,946			$17,123			$15,890
Supplemental Ratios (%):
Ratio of expenses to average net assets after expense reductions excluding short sale expenses (f)		1.42	(a)		1.45	(c)		1.49			1.52			1.54			1.62

See Notes to Financial Statements

Financial Highlights – continued


	Six months ended 2/28/18			Year ended
Class R3	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14			8/31/13
	(unaudited)

Net asset value, beginning of period		$35.66			$28.26			$24.61			$24.46			$19.41			$16.80
Income (loss) from investment operations
Net investment income (loss) (d)		$(0.12	)		$(0.20	)(c)		$(0.13	)		$(0.15	)		$(0.13	)		$(0.12	)
Net realized and unrealized gain (loss)		5.88			8.14			4.77			1.15			5.18			2.73
Total from investment operations		$5.76			$7.94			$4.64			$1.00			$5.05			$2.61
Less distributions declared to shareholders
From net realized gain		$(1.37	)		$(0.54	)		$(0.99	)		$(0.85	)		$—			$—
Net asset value, end of period (x)		$40.05			$35.66			$28.26			$24.61			$24.46			$19.41
Total return (%) (r)(s)(t)(x)		16.53	(n)		28.59	(c)		19.21			4.18			26.02			15.54
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.19	(a)		1.24	(c)		1.27			1.30			1.33			1.55
Expenses after expense reductions (f)		1.18	(a)		1.23	(c)		1.26			1.29			1.32			1.55
Net investment income (loss)		(0.62	)(a)		(0.65	)(c)		(0.49	)		(0.60	)		(0.59	)		(0.70	)
Portfolio turnover		18	(n)		43			30			43			38			54
Net assets at end of period (000 omitted)		$65,021			$53,199			$20,180			$9,732			$10,626			$8,863
Supplemental Ratios (%):
Ratio of expenses to average net assets after expense reductions excluding short sale expenses (f)		1.17	(a)		1.20	(c)		1.25			1.27			1.29			1.37

See Notes to Financial Statements

Financial Highlights – continued


	Six months ended 2/28/18			Year ended
Class R4	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14			8/31/13
	(unaudited)

Net asset value, beginning of period		$36.95			$29.19			$25.34			$25.10			$19.86			$17.15
Income (loss) from investment operations
Net investment income (loss) (d)		$(0.07	)		$(0.13	)(c)		$(0.06	)		$(0.09	)		$(0.08	)		$(0.08	)
Net realized and unrealized gain (loss)		6.10			8.43			4.90			1.18			5.32			2.79
Total from investment operations		$6.03			$8.30			$4.84			$1.09			$5.24			$2.71
Less distributions declared to shareholders
From net realized gain		$(1.37	)		$(0.54	)		$(0.99	)		$(0.85	)		$—			$—
Net asset value, end of period (x)		$41.61			$36.95			$29.19			$25.34			$25.10			$19.86
Total return (%) (r)(s)(t)(x)		16.69	(n)		28.92	(c)		19.45			4.44			26.38			15.80
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		0.94	(a)		0.99	(c)		1.02			1.05			1.07			1.29
Expenses after expense reductions (f)		0.93	(a)		0.99	(c)		1.01			1.04			1.07			1.29
Net investment income (loss)		(0.37	)(a)		(0.39	)(c)		(0.24	)		(0.37	)		(0.34	)		(0.45	)
Portfolio turnover		18	(n)		43			30			43			38			54
Net assets at end of period (000 omitted)		$17,910			$14,443			$8,141			$2,234			$1,403			$1,269
Supplemental Ratios (%):
Ratio of expenses to average net assets after expense reductions excluding short sale expenses (f)		0.92	(a)		0.95	(c)		1.00			1.02			1.04			1.12

See Notes to Financial Statements

Financial Highlights – continued


	Six months ended 2/28/18			Year ended
Class R6	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14			8/31/13 (i)
	(unaudited)

Net asset value, beginning of period		$38.09			$30.05			$26.03			$25.73			$20.34			$17.68
Income (loss) from investment operations
Net investment income (loss) (d)		$(0.05	)		$(0.10	)(c)		$(0.04	)		$(0.07	)		$(0.07	)		$(0.04	)
Net realized and unrealized gain (loss)		6.29			8.68			5.05			1.22			5.46			2.70
Total from investment operations		$6.24			$8.58			$5.01			$1.15			$5.39			$2.66
Less distributions declared to shareholders
From net realized gain		$(1.37	)		$(0.54	)		$(0.99	)		$(0.85	)		$—			$—
Net asset value, end of period (x)		$42.96			$38.09			$30.05			$26.03			$25.73			$20.34
Total return (%) (r)(s)(t)(x)		16.74	(n)		29.03	(c)		19.59			4.57			26.50			15.05	(n)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		0.85	(a)		0.90	(c)		0.92			0.95			0.97			1.13	(a)
Expenses after expense reductions (f)		0.84	(a)		0.89	(c)		0.91			0.94			0.96			1.13	(a)
Net investment income (loss)		(0.27	)(a)		(0.30	)(c)		(0.13	)		(0.27	)		(0.28	)		(0.35	)(a)
Portfolio turnover		18	(n)		43			30			43			38			54
Net assets at end of period (000 omitted)		$106,990			$95,534			$33,411			$7,079			$2,429			$116
Supplemental Ratios (%):
Ratio of expenses to average net assets after expense reductions excluding short sale expenses (f)		0.83	(a)		0.85	(c)		0.90			0.92			0.95			1.01	(a)

(a)	Annualized.

(c)	Amount reflects a one-time reimbursement of expenses by the custodian (or former custodian) without which net investment income and performance would be lower and expenses would be higher.

(d)	Per share data is based on average shares outstanding.

(f)	Ratios do not reflect reductions from fees paid indirectly, if applicable.

(i)	For the period from the class inception, January 2, 2013, through the stated period end.

(n)	Not annualized.

(r)	Certain expenses have been reduced without which performance would have been lower.

(s)	From time to time the fund may receive proceeds from litigation settlements, without which performance would be lower.

(t)	Total returns do not include any applicable sales charges.

(x)	The net asset values and total returns have been calculated on net assets which include adjustments made in accordance with U.S. generally accepted accounting principles required at period end for financial reporting purposes.

See Notes to Financial Statements

NOTES TO FINANCIAL STATEMENTS

(unaudited)

(1) Business and Organization

MFS Technology Fund (the fund) is a non-diversified series of MFS Series Trust I (the trust). The trust is organized as a Massachusetts business trust and is registered under the Investment Company Act of 1940, as amended, as an open-end management investment company.

(2) Significant Accounting Policies

General – The preparation of financial statements in conformity with U.S. generally accepted accounting principles requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of increases and decreases in net assets from operations during the reporting period. Actual results could differ from those estimates. In the preparation of these financial statements, management has evaluated subsequent events occurring after the date of the fund’s Statement of Assets and Liabilities through the date that the financial statements were issued. The fund invests primarily in securities of issuers in the technology industry. Issuers in a single industry can react similarly to market, currency, political, economic, regulatory, geopolitical, and other conditions. The value of stocks in the technology sector can be very volatile due to the rapid pace of product change, technological developments, and other factors.

Notes to Financial Statements (unaudited) – continued

amortized cost, which approximates market value. Open-end investment companies are generally valued at net asset value per share. Securities and other assets generally valued on the basis of information from a third-party pricing service may also be valued at a broker/dealer bid quotation. Values obtained from third-party pricing services can utilize both transaction data and market information such as yield, quality, coupon rate, maturity, type of issue, trading characteristics, and other market data. The values of foreign securities and other assets and liabilities expressed in foreign currencies are converted to U.S. dollars using the mean of bid and asked prices for rates provided by a third-party pricing service.

Notes to Financial Statements (unaudited) – continued

judgment, and considers factors specific to the investment. Level 1 includes unadjusted quoted prices in active markets for identical assets or liabilities. Level 2 includes other significant observable market-based inputs (including quoted prices for similar securities, interest rates, prepayment speed, and credit risk). Level 3 includes unobservable inputs, which may include the adviser’s own assumptions in determining the fair value of investments. The following is a summary of the levels used as of February 28, 2018 in valuing the fund’s assets or liabilities:


Financial Instruments	Level 1			Level 2		Level 3		Total
Equity Securities		$992,309,723			$—		$—		$992,309,723
Mutual Funds		12,265,511			—		—		12,265,511
Total		$1,004,575,234			$—		$—		$1,004,575,234
Securities Sold Short		$(4,445,426	)		$—		$—		$(4,445,426	)

For further information regarding security characteristics, see the Portfolio of Investments.

Short Sales – The fund entered into short sales whereby it sells a security it does not own in anticipation of a decline in the value of that security. The fund will realize a gain if the security price decreases and a loss if the security price increases between the date of the short sale and the date on which the fund replaces the borrowed security. Losses from short sales can exceed the proceeds of the security sold; and they can also exceed the potential loss from an ordinary buy and sell transaction. The amount of any premium, dividends, or interest the fund may be required to pay in connection with a short sale will be recognized as a fund expense. During the six months ended February 28, 2018, this expense amounted to $66,394. The fund segregates cash or marketable securities in an amount that, when combined with the amount of proceeds from the short sale deposited with the broker, at least equals the current market value of the security sold short.

Notes to Financial Statements (unaudited) – continued

market value of the loaned securities is determined at the close of business of the fund and any additional required collateral is delivered to the fund on the next business day. State Street provides the fund with indemnification against Borrower default. In the event of Borrower default, State Street will, for the benefit of the fund, either purchase securities identical to those loaned or, when such purchase is commercially impracticable, pay the fund the market value of the loaned securities. In return, State Street assumes the fund’s rights to the related collateral. If the collateral value is less than the cost to purchase identical securities, State Street is responsible for the shortfall, but only to the extent that such shortfall is not due to a decline in collateral value resulting from collateral reinvestment for which the fund bears the risk of loss. At period end, the fund had investment securities on loan, all of which were classified as equity securities in the fund’s Portfolio of Investments, with a fair value of $3,906,858. The fair value of the fund’s investment securities on loan and a related liability of $2,647,798 for cash collateral received on securities loaned are both presented gross in the Statement of Assets and Liabilities. Additionally, these loans were collateralized by U.S. Treasury Obligations of $1,410,456. The collateral on securities loaned exceeded the value of securities on loan at period end. The liability for cash collateral for securities loaned is carried at fair value, which is categorized as level 2 within the fair value hierarchy. A portion of the income generated upon investment of the collateral is remitted to the Borrowers, and the remainder is allocated between the fund and the lending agent. On loans collateralized by U.S. Treasury and/or federal agency obligations, a fee is received from the Borrower, and is allocated between the fund and the lending agent. Income from securities lending is separately reported in the Statement of Operations. The dividend and interest income earned on the securities loaned is accounted for in the same manner as other dividend and interest income.

Notes to Financial Statements (unaudited) – continued

Book/tax differences primarily relate to wash sale loss deferrals, straddle loss deferrals, and treating a portion of the proceeds from redemptions as a distribution for tax purposes.


	Year ended 8/31/17
Long-term capital gains		$12,086,828

Notes to Financial Statements (unaudited) – continued

The federal tax cost and the tax basis components of distributable earnings were as follows:


As of 2/28/18
Cost of investments	$579,544,681
Gross appreciation	426,096,209
Gross depreciation	(5,511,082	)
Net unrealized appreciation (depreciation)	$420,585,127

As of 8/31/17
Undistributed ordinary income	10,345,364
Undistributed long-term capital gain	23,675,811
Other temporary differences	(627	)
Net unrealized appreciation (depreciation)	309,662,825

The aggregate cost above includes prior fiscal year end tax adjustments, if applicable.


	From net realized gain on investments
	Six months ended 2/28/18		Year ended 8/31/17
Class A		$13,806,022		$6,042,407
Class B		1,454,317		564,793
Class C		4,487,570		1,649,827
Class I		6,827,614		1,747,655
Class R1		182,847		62,501
Class R2		964,012		357,143
Class R3		2,088,034		493,168
Class R4		546,050		176,204
Class R6		3,665,758		993,130
Total		$34,022,224		$12,086,828

Notes to Financial Statements (unaudited) – continued

(3) Transactions with Affiliates


Up to $1 billion	0.75	%
In excess of $1 billion	0.70	%

MFS has agreed in writing to reduce its management fee by a specified amount if certain MFS mutual fund assets exceed thresholds agreed to by MFS and the fund’s Board of Trustees. For the six months ended February 28, 2018, this management fee reduction amounted to $39,399, which is included in the reduction of total expenses in the Statement of Operations. The management fee incurred for the six months ended February 28, 2018 was equivalent to an annual effective rate of 0.74% of the fund’s average daily net assets.

Distributor – MFS Fund Distributors, Inc. (MFD), a wholly-owned subsidiary of MFS, as distributor, received $100,533 for the six months ended February 28, 2018, as its portion of the initial sales charge on sales of Class A shares of the fund.

The Board of Trustees has adopted a distribution plan for certain share classes pursuant to Rule 12b-1 of the Investment Company Act of 1940.

Distribution Plan Fee Table:


	Distribution Fee Rate (d)		Service Fee Rate (d)		Total Distribution Plan (d)		Annual Effective Rate (e)		Distribution and Service Fee
Class A		—		0.25%		0.25%		0.24%		$469,723
Class B		0.75%		0.25%		1.00%		1.00%		176,658
Class C		0.75%		0.25%		1.00%		1.00%		541,723
Class R1		0.75%		0.25%		1.00%		1.00%		22,603
Class R2		0.25%		0.25%		0.50%		0.50%		62,458
Class R3		—		0.25%		0.25%		0.25%		71,645
Total Distribution and Service Fees										$1,344,810

(d)

(e)

The annual effective rates represent actual fees incurred under the distribution plan for the six months ended February 28, 2018 based on each class’s average daily net assets. MFD has voluntarily agreed to rebate a portion of each class’s 0.25% service fee attributable to accounts for which MFD retains the 0.25% service fee except for accounts attributable to MFS or its affiliates’ seed money. For the six months ended February 28, 2018, this rebate amounted to $8,912, $324, and $518 for Class A, Class B, and Class C, respectively, and is included in the reduction of total expenses in the Statement of Operations.

Notes to Financial Statements (unaudited) – continued


	Amount
Class A		$1,448
Class B		18,398
Class C		6,052

Shareholder Servicing Agent – MFS Service Center, Inc. (MFSC), a wholly-owned subsidiary of MFS, receives a fee from the fund for its services as shareholder servicing agent calculated as a percentage of the average daily net assets of the fund as determined periodically under the supervision of the fund’s Board of Trustees. For the six months ended February 28, 2018, the fee was $80,283, which equated to 0.0175% annually of the fund’s average daily net assets. MFSC also receives payment from the fund for out-of-pocket expenses, sub-accounting and other shareholder servicing costs which may be paid to affiliated and unaffiliated service providers. Class R6 shares do not incur sub-accounting fees. For the six months ended February 28, 2018, these out-of-pocket expenses, sub-accounting and other shareholder servicing costs amounted to $423,492.

Prior to December 31, 2001, the fund had an unfunded defined benefit plan (“DB plan”) for independent Trustees. As of December 31, 2001, the Board took action to terminate the DB plan with respect to then-current and any future independent Trustees, such that the DB plan covers only certain of those former independent Trustees who retired on or before December 31, 2001. The DB plan resulted in a pension expense of $130 and is included in “Independent Trustees’ compensation” in the Statement of Operations for the six months ended February 28, 2018. The liability for deferred retirement benefits payable to certain independent Trustees under the DB plan amounted to $564 at February 28, 2018, and is included in “Payable for independent Trustees’ compensation” in the Statement of Assets and Liabilities.

Notes to Financial Statements (unaudited) – continued

Other – This fund and certain other funds managed by MFS (the funds) have entered into a service agreement (the ISO Agreement) which provides for payment of fees solely by the funds to Tarantino LLC in return for the provision of services of an Independent Senior Officer (ISO) for the funds. Frank L. Tarantino serves as the ISO and is an officer of the funds and the sole member of Tarantino LLC. The funds can terminate the ISO Agreement with Tarantino LLC at any time under the terms of the ISO Agreement. For the six months ended February 28, 2018, the fee paid by the fund under this agreement was $731 and is included in “Miscellaneous” expense in the Statement of Operations. MFS has agreed to bear all expenses associated with office space, other administrative support, and supplies provided to the ISO.

The fund is permitted to engage in purchase and sale transactions with funds and accounts for which MFS serves as investment adviser or sub-adviser (“cross-trades”) pursuant to a policy adopted by the Board of Trustees. This policy has been designed to ensure that cross-trades conducted by the fund comply with Rule 17a-7 under the Investment Company Act of 1940. During the six months ended February 28, 2018, the fund engaged in sale transactions pursuant to this policy, which amounted to $274,561. The sales transactions resulted in net realized gains (losses) of $46,534.

(4) Portfolio Securities

For the six months ended February 28, 2018, purchases and sales of investments, other than short sales and short-term obligations, aggregated $173,564,530 and $165,312,484, respectively.

Notes to Financial Statements (unaudited) – continued

(5) Shares of Beneficial Interest

The fund’s Declaration of Trust permits the Trustees to issue an unlimited number of full and fractional shares of beneficial interest. Transactions in fund shares were as follows:


	Six months ended 2/28/18						Year ended 8/31/17
	Shares			Amount			Shares			Amount
Shares sold
Class A		1,070,770			$40,364,124			3,903,397			$118,724,794
Class B		120,079			3,988,559			300,442			8,204,144
Class C		413,499			13,588,850			1,045,012			28,144,392
Class I		1,267,003			51,001,662			3,330,760			106,868,431
Class R1		28,124			921,484			53,395			1,439,175
Class R2		144,737			5,182,431			317,338			9,295,803
Class R3		400,216			15,185,975			1,128,979			34,581,757
Class R4		104,971			4,130,636			186,687			5,801,786
Class R6		746,250			30,288,320			1,876,424			59,960,695
		4,295,649			$164,652,041			12,142,434			$373,020,977

Shares issued to shareholders in reinvestment of distributions
Class A		360,827			$13,188,223			206,974			$5,813,904
Class B		45,085			1,435,497			22,405			555,187
Class C		130,689			4,151,976			59,252			1,465,308
Class I		150,118			5,847,113			42,956			1,279,665
Class R1		5,742			182,089			2,532			62,501
Class R2		24,374			851,394			11,665			314,359
Class R3		57,144			2,088,033			17,563			493,168
Class R4		11,457			434,687			4,712			136,848
Class R6		74,971			2,935,862			23,250			695,648
		860,407			$31,114,874			391,309			$10,816,588

Shares reacquired
Class A		(1,421,325	)		$(53,189,702	)		(5,378,740	)		$(165,793,400	)
Class B		(161,322	)		(5,277,184	)		(261,310	)		(7,226,145	)
Class C		(341,519	)		(11,189,933	)		(772,303	)		(21,102,926	)
Class I		(940,694	)		(37,872,761	)		(2,006,437	)		(64,179,030	)
Class R1		(26,527	)		(867,826	)		(42,550	)		(1,112,429	)
Class R2		(175,462	)		(6,331,114	)		(264,457	)		(7,811,141	)
Class R3		(325,754	)		(12,218,159	)		(368,711	)		(11,215,693	)
Class R4		(76,860	)		(3,033,423	)		(79,423	)		(2,549,379	)
Class R6		(838,765	)		(33,152,884	)		(503,418	)		(16,400,155	)
		(4,308,228	)		$(163,132,986	)		(9,677,349	)		$(297,390,298	)

Notes to Financial Statements (unaudited) – continued


	Six months ended 2/28/18						Year ended 8/31/17
	Shares			Amount			Shares			Amount
Net change
Class A		10,272			$362,645			(1,268,369	)		$(41,254,702	)
Class B		3,842			146,872			61,537			1,533,186
Class C		202,669			6,550,893			331,961			8,506,774
Class I		476,427			18,976,014			1,367,279			43,969,066
Class R1		7,339			235,747			13,377			389,247
Class R2		(6,351	)		(297,289	)		64,546			1,799,021
Class R3		131,606			5,055,849			777,831			23,859,232
Class R4		39,568			1,531,900			111,976			3,389,255
Class R6		(17,544	)		71,298			1,396,256			44,256,188
		847,828			$32,633,929			2,856,394			$86,447,267

Class T shares were not publicly available for sale during the period. Please see the fund’s prospectus for details.

(6) Line of Credit

The fund and certain other funds managed by MFS participate in a $1.25 billion unsecured committed line of credit, subject to a $1 billion sublimit, provided by a syndication of banks under a credit agreement. Borrowings may be made for temporary financing needs. Interest is charged to each fund, based on its borrowings, generally at a rate equal to the higher of the Overnight Federal Reserve funds rate or daily one month LIBOR plus an agreed upon spread. A commitment fee, based on the average daily, unused portion of the committed line of credit, is allocated among the participating funds at the end of each calendar quarter. In addition, the fund and other funds managed by MFS have established unsecured uncommitted borrowing arrangements with certain banks for temporary financing needs. Interest is charged to each fund, based on its borrowings, at a rate equal to the Overnight Federal Reserve funds rate plus an agreed upon spread. For the six months ended February 28, 2018, the fund’s commitment fee and interest expense were $2,728 and $0, respectively, and are included in “Miscellaneous” expense in the Statement of Operations.

(7) Investments in Affiliated Issuers


Affiliated Issuers				Beginning Shares/Par Amount		Acquisitions Shares/Par Amount		Dispositions Shares/Par Amount			Ending Shares/Par Amount
MFS Institutional Money Market Portfolio					24,817,058		105,097,492		(120,295,875	)		9,618,675

Affiliated Issuers	Realized Gain (Loss)			Change in Unrealized Appreciation (Depreciation)		Capital Gain Distributions		Dividend Income			Ending Value
MFS Institutional Money Market Portfolio		$(2,455	)		$39		$—		$92,742			$9,617,713

PROXY VOTING POLICIES AND INFORMATION

QUARTERLY PORTFOLIO DISCLOSURE

Public Reference Room

Securities and Exchange Commission

100 F Street, NE, Room 1580

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PROVISION OF FINANCIAL REPORTS AND SUMMARY PROSPECTUSES

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MAILING ADDRESS

MFS Service Center, Inc.

P.O. Box 55824

Boston, MA 02205-5824

OVERNIGHT MAIL

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c/o DST Asset Manager Solutions, Inc.

30 Dan Road

Canton, MA 02021-2809

Semiannual Report

February 28, 2018

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MFS® U.S. Government Cash Reserve Fund

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LMM-SEM

MFS® U.S. Government Cash Reserve Fund

CONTENTS


Letter from the Executive Chairman			1
Portfolio composition			2
Expense table			3
Portfolio of investments			5
Statement of assets and liabilities			7
Statement of operations			9
Statements of changes in net assets			10
Financial highlights			11
Notes to financial statements			21
Proxy voting policies and information			30
Quarterly portfolio disclosure			30
Further information			30
Information about fund contracts and legal claims			31
Provision of financial reports and summary prospectuses			31
Contact information back cover

The report is prepared for the general information of shareholders.

It is authorized for distribution to prospective investors only when preceded or accompanied by a current prospectus.

NOT FDIC INSURED • MAY LOSE VALUE • NO BANK GUARANTEE

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LETTER FROM THE EXECUTIVE CHAIRMAN

Dear Shareholders:

Rising bond yields have led to a measurable uptick in market volatility — a departure from the low-volatility environment that prevailed for much of 2017. In spite of this,

U.S. protectionism is also a growing concern, as investors fear that trade friction could disrupt the synchronized uptick in global growth.

Respectfully,

LOGO

Robert J. Manning

Executive Chairman

MFS Investment Management

April 13, 2018

The opinions expressed in this letter are subject to change and may not be relied upon for investment advice. No forecasts can be guaranteed.

PORTFOLIO COMPOSITION

Portfolio structure (u)

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Composition including fixed income credit quality (a)(u)
A-1+			13.0%
A-1			79.5%
A-2			7.8%
Other Assets Less Liabilities			(0.3)%


Maturity breakdown (u)
0 - 7 days			25.3%
8 - 29 days			16.7%
30 - 59 days			53.0%
90 - 365 days			5.3%
Other Assets Less Liabilities			(0.3)%

(a)

Ratings are assigned to portfolio securities utilizing ratings from Moody’s, Fitch, and Standard & Poor’s rating agencies and applying the following hierarchy: If all three agencies provide a rating, the middle rating (after dropping the highest and lowest ratings) is assigned; if two of the three agencies rate a security, the lower of the two is assigned. Ratings are shown in the S&P scale. All ratings are subject to change. The fund did not hold unrated securities. The fund is not rated by these agencies.

(u)	For purposes of this presentation, accrued interest, where applicable, is included.

From time to time Other Assets Less Liabilities may be negative due to timing of cash receipts.

Percentages are based on net assets as of February 28, 2018.

The portfolio is actively managed and current holdings may be different.

EXPENSE TABLE

Fund expenses borne by the shareholders during the period, September 1, 2017 through February 28, 2018

The example is based on an investment of $1,000 invested at the beginning of the period and held for the entire period September 1, 2017 through February 28, 2018.

Actual Expenses

Hypothetical Example for Comparison Purposes

Expense Table – continued


Share Class		Annualized Expense Ratio		Beginning Account Value 9/01/17		Ending Account Value 2/28/18		Expenses Paid During Period (p) 9/01/17-2/28/18
A	Actual		0.69%		$1,000.00		$1,002.30		$3.43
A	Hypothetical (h)		0.69%		$1,000.00		$1,021.37		$3.46
B	Actual		0.69%		$1,000.00		$1,002.30		$3.43
B	Hypothetical (h)		0.69%		$1,000.00		$1,021.37		$3.46
C	Actual		0.69%		$1,000.00		$1,002.30		$3.43
C	Hypothetical (h)		0.69%		$1,000.00		$1,021.37		$3.46
R1	Actual		0.68%		$1,000.00		$1,002.30		$3.38
R1	Hypothetical (h)		0.68%		$1,000.00		$1,021.42		$3.41
R2	Actual		0.68%		$1,000.00		$1,002.30		$3.38
R2	Hypothetical (h)		0.68%		$1,000.00		$1,021.42		$3.41
R3	Actual		0.68%		$1,000.00		$1,002.30		$3.38
R3	Hypothetical (h)		0.68%		$1,000.00		$1,021.42		$3.41
R4	Actual		0.68%		$1,000.00		$1,002.31		$3.38
R4	Hypothetical (h)		0.68%		$1,000.00		$1,021.42		$3.41
529A	Actual		0.73%		$1,000.00		$1,002.05		$3.62
529A	Hypothetical (h)		0.73%		$1,000.00		$1,021.17		$3.66
529B	Actual		0.73%		$1,000.00		$1,002.05		$3.62
529B	Hypothetical (h)		0.73%		$1,000.00		$1,021.17		$3.66
529C	Actual		0.73%		$1,000.00		$1,002.05		$3.62
529C	Hypothetical (h)		0.73%		$1,000.00		$1,021.17		$3.66

(h)	5% class return per year before expenses.

(p)

PORTFOLIO OF INVESTMENTS

2/28/18 (unaudited)

The Portfolio of Investments is a complete list of all securities owned by your fund. It is categorized by broad-based asset classes.


U.S. Government Agencies and Equivalents (y) - 92.5%
Issuer	Shares/Par		Value ($)
Fannie Mae, 1.315%, due 3/01/2018	$	5,600,000	$	5,600,000
Fannie Mae, 1.299%, due 3/05/2018		7,700,000		7,698,905
Fannie Mae, 1.307%, due 3/07/2018		8,000,000		7,998,283
Fannie Mae, 1.319%, due 3/14/2018		5,326,000		5,323,500
Fannie Mae, 1.392%, due 4/02/2018		9,866,000		9,853,985
Fannie Mae, 1.473%, due 4/09/2018		9,800,000		9,784,606
Federal Farm Credit Bank, 1.331%, due 3/16/2018		7,200,000		7,196,070
Federal Farm Credit Bank, 1.341%, due 3/19/2018		1,000,000		999,340
Federal Farm Credit Bank, 1.39%, due 3/22/2018		3,600,000		3,597,123
Federal Farm Credit Bank, 1.472%, due 3/27/2018		10,000,000		9,989,528
Federal Farm Credit Bank, 1.545%, due 4/11/2018		6,667,000		6,655,459
Federal Farm Credit Bank, 1.434%, due 4/24/2018		5,000,000		4,989,425
Federal Farm Credit Bank, 1.546%, due 4/24/2018		6,000,000		5,986,320
Federal Farm Credit Bank, 1.434%, due 4/26/2018		9,500,000		9,479,163
Federal Home Loan Bank, 1.329%, due 3/02/2018		11,780,000		11,779,571
Federal Home Loan Bank, 1.361%, due 3/02/2018		9,600,000		9,599,643
Federal Home Loan Bank, 1.369%, due 3/09/2018		11,500,000		11,496,550
Federal Home Loan Bank, 1.335%, due 3/12/2018		2,000,000		1,999,196
Federal Home Loan Bank, 1.554%, due 4/05/2018		14,200,000		14,178,877
Freddie Mac, 1.37%, due 3/14/2018		100,000		99,951
Freddie Mac, 1.346%, due 4/04/2018		10,100,000		10,087,361
Freddie Mac, 1.347%, due 4/10/2018		9,800,000		9,785,572
Freddie Mac, 1.473%, due 4/10/2018		4,200,000		4,193,233
Freddie Mac, 1.347%, due 4/11/2018		9,800,000		9,785,212
Freddie Mac, 1.383%, due 4/23/2018		10,500,000		10,478,977
Freddie Mac, 1.475%, due 4/24/2018		5,000,000		4,989,125
U.S. Treasury Bill, 1.519%, due 4/12/2018		10,881,000		10,862,022
U.S. Treasury Bill, 1.44%, due 4/26/2018		8,000,000		7,982,391
U.S. Treasury Bill, 1.594%, due 7/12/2018		7,000,000		6,959,657
U.S. Treasury Bill, 1.594%, due 7/12/2018		1,000,000		994,237
U.S. Treasury Bill, 1.785%, due 1/03/2019		5,000,000		4,925,994
Total U.S. Government Agencies and Equivalents, at Amortized Cost and Value			$	225,349,276

Repurchase Agreements - 7.8%
Goldman Sachs Repurchase Agreement, 1.38%, dated 2/28/2018, due 3/01/2018, total to be received $11,945,458 (secured by U.S. Federal Agency obligations valued at $12,183,954 in a jointly traded account), at Cost and Value	$	11,945,000	$	11,945,000

Portfolio of Investments (unaudited) – continued


Issuer	Shares/Par		Value ($)
Repurchase Agreements - continued
JPMorgan Chase & Co. Repurchase Agreement, 1.35%, dated 2/28/2018, due 3/01/2018, total to be received $7,000,263 (secured by U.S. Federal Agency obligations valued at $7,144,744 in a jointly traded account), at Cost and Value	$	7,000,000	$	7,000,000
Total Repurchase Agreements, at Cost and Value			$	18,945,000

Other Assets, Less Liabilities - (0.3)%				(835,082	)
Net Assets - 100.0%			$	243,459,194

(y)	The rate shown represents an annualized yield at time of purchase.

See Notes to Financial Statements

Financial Statements

STATEMENT OF ASSETS AND LIABILITIES

At 2/28/18 (unaudited)

This statement represents your fund’s balance sheet, which details the assets and liabilities comprising the total value of the fund.


Assets
Investments in unaffiliated issuers, at amortized cost and value	$244,294,276
Cash	613
Receivables for
Fund shares sold	514,338
Interest	720
Other assets	1,323
Total assets	$244,811,270
Liabilities
Payables for
Distributions	$2,097
Fund shares reacquired	1,208,225
Payable to affiliates
Investment adviser	5,488
Shareholder servicing costs	103,009
Program manager fee	57
Payable for independent Trustees’ compensation	5,932
Accrued expenses and other liabilities	27,268
Total liabilities	$1,352,076
Net assets	$243,459,194
Net assets consist of
Paid-in capital	$243,466,918
Accumulated net realized gain (loss)	(5	)
Accumulated distributions in excess of net investment income	(7,719	)
Net assets	$243,459,194
Shares of beneficial interest outstanding	243,689,201

Statement of Assets and Liabilities (unaudited) – continued


	Net assets		Shares outstanding			Net asset value per share
Class A		$95,004,202		95,089,305			$1.00
Class B		14,712,378		14,729,220			1.00
Class C		32,902,407		32,942,700			1.00
Class R1		8,910,482		8,920,332			1.00
Class R2		37,966,901		38,002,645	��		1.00
Class R3		30,555,838		30,583,727			1.00
Class R4		2,708,131		2,710,074			1.00
Class 529A		13,270,809		13,278,241			1.00
Class 529B		328,734		329,212			1.00
Class 529C		7,099,312		7,103,745			1.00

A contingent deferred sales charge may be imposed on redemptions of Class A, Class B, Class C, Class 529B, and Class 529C shares. Redemption price per share was equal to the net asset value per share for Classes R1, R2, R3, R4, and 529A. Net asset value per share is calculated using actual net assets and shares outstanding rather than amounts that have been rounded for presentation purposes.

See Notes to Financial Statements

Financial Statements

STATEMENT OF OPERATIONS

Six months ended 2/28/18 (unaudited)

This statement describes how much your fund earned in investment income and accrued in expenses. It also describes any gains and/or losses generated by fund operations.


Net investment income (loss)
Income
Interest	$1,475,420
Expenses
Management fee	$516,381
Distribution and service fees	629,357
Shareholder servicing costs	237,108
Program manager fees	7,856
Administrative services fee	24,378
Independent Trustees’ compensation	5,246
Custodian fee	10,193
Shareholder communications	9,995
Audit and tax fees	18,219
Legal fees	1,692
Miscellaneous	72,251
Total expenses	$1,532,676
Reduction of expenses by investment adviser and distributor	(643,290	)
Net expenses	$889,386
Net investment income (loss)	$586,034
Change in net assets from operations	$586,034

See Notes to Financial Statements

Financial Statements

STATEMENTS OF CHANGES IN NET ASSETS

These statements describe the increases and/or decreases in net assets resulting from operations, any distributions, and any shareholder transactions.


Change in net assets	Six months ended 2/28/18 (unaudited)			Year ended 8/31/17
From operations
Net investment income (loss)		$586,034			$227,430
Net realized gain (loss)		—			(4	)
Change in net assets from operations		$586,034			$227,426
Distributions declared to shareholders
From net investment income		$(586,034	)		$(227,426	)
Change in net assets from fund share transactions		$(37,574,130	)		$(33,308,224	)
Total change in net assets		$(37,574,130	)		$(33,308,224	)
Net assets
At beginning of period		281,033,324			314,341,548
At end of period (including accumulated distributions in excess of net investment income of $7,719 and $7,719, respectively)		$243,459,194			$281,033,324

See Notes to Financial Statements

Financial Statements

FINANCIAL HIGHLIGHTS


	Six months ended 2/28/18			Year ended
Class A	Six months ended 2/28/18			8/31/17			8/31/16		8/31/15			8/31/14			8/31/13
	(unaudited)
Net asset value, beginning of period		$1.00			$1.00			$1.00		$1.00			$1.00			$1.00
Income (loss) from investment operations
Net investment income (loss) (d)		$0.00	(w)		$0.00	(c)(w)		$0.00		$0.00			$0.00			$0.00
Net realized and unrealized gain (loss)		—			(0.00	)(w)		—		0.00	(w)		0.00	(w)		—
Total from investment operations		$0.00	(w)		$0.00	(w)		$0.00		$0.00	(w)		$0.00	(w)		$0.00
Less distributions declared to shareholders
From net investment income		$(0.00	)(w)		$(0.00	)(w)		$—		$—			$—			$—
Net asset value, end of period		$1.00			$1.00			$1.00		$1.00			$1.00			$1.00
Total return (%) (r)(t)		0.23	(n)		0.08	(c)		0.00		0.00	(w)		0.00	(w)		0.00
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		0.94	(a)		0.91	(c)		0.91		0.92			0.90			0.93
Expenses after expense reductions (f)		0.69	(a)		0.50	(c)		0.23		0.07			0.09			0.15
Net investment income (loss)		0.46	(a)		0.08	(c)		0.00		0.00			0.00			0.00
Net assets at end of period (000 omitted)		$95,004			$105,859			$120,740		$122,085			$124,550			$145,062

See Notes to Financial Statements

Financial Highlights – continued


	Six months ended 2/28/18			Year ended
Class B	Six months ended 2/28/18			8/31/17			8/31/16		8/31/15			8/31/14			8/31/13
	(unaudited)
Net asset value, beginning of period		$1.00			$1.00			$1.00		$1.00			$1.00			$1.00
Income (loss) from investment operations
Net investment income (loss) (d)		$0.00	(w)		$0.00	(c)(w)		$0.00		$0.00			$0.00			$0.00
Net realized and unrealized gain (loss)		—			(0.00	)(w)		—		0.00	(w)		0.00	(w)		—
Total from investment operations		$0.00	(w)		$0.00	(w)		$0.00		$0.00	(w)		$0.00	(w)		$0.00
Less distributions declared to shareholders
From net investment income		$(0.00	)(w)		$(0.00	)(w)		$—		$—			$—			$—
Net asset value, end of period		$1.00			$1.00			$1.00		$1.00			$1.00			$1.00
Total return (%) (r)(t)		0.23	(n)		0.08	(c)		0.00		0.00	(w)		0.00	(w)		0.00
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.69	(a)		1.66	(c)		1.66		1.67			1.65			1.68
Expenses after expense reductions (f)		0.69	(a)		0.51	(c)		0.23		0.07			0.10			0.15
Net investment income (loss)		0.46	(a)		0.07	(c)		0.00		0.00			0.00			0.00
Net assets at end of period (000 omitted)		$14,712			$17,338			$18,096		$18,831			$22,982			$30,833

See Notes to Financial Statements

Financial Highlights – continued


	Six months ended 2/28/18			Year ended
Class C	Six months ended 2/28/18			8/31/17			8/31/16		8/31/15			8/31/14			8/31/13
	(unaudited)
Net asset value, beginning of period		$1.00			$1.00			$1.00		$1.00			$1.00			$1.00
Income (loss) from investment operations
Net investment income (loss) (d)		$0.00	(w)		$0.00	(c)(w)		$0.00		$0.00			$0.00			$0.00
Net realized and unrealized gain (loss)		—			(0.00	)(w)		—		0.00	(w)		0.00	(w)		—
Total from investment operations		$0.00	(w)		$0.00	(w)		$0.00		$0.00	(w)		$0.00	(w)		$0.00
Less distributions declared to shareholders
From net investment income		$(0.00	)(w)		$(0.00	)(w)		$—		$—			$—			$—
Net asset value, end of period		$1.00			$1.00			$1.00		$1.00			$1.00			$1.00
Total return (%) (r)(t)		0.23	(n)		0.08	(c)		0.00		0.00	(w)		0.00	(w)		0.00
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.69	(a)		1.66	(c)		1.66		1.67			1.65			1.68
Expenses after expense reductions (f)		0.69	(a)		0.50	(c)		0.24		0.07			0.10			0.15
Net investment income (loss)		0.46	(a)		0.07	(c)		0.00		0.00			0.00			0.00
Net assets at end of period (000 omitted)		$32,902			$38,458			$48,749		$42,522			$45,662			$58,363

See Notes to Financial Statements

Financial Highlights – continued


	Six months ended 2/28/18			Year ended
Class R1	Six months ended 2/28/18			8/31/17			8/31/16		8/31/15			8/31/14			8/31/13
	(unaudited)
Net asset value, beginning of period		$1.00			$1.00			$1.00		$1.00			$1.00			$1.00
Income (loss) from investment operations
Net investment income (loss) (d)		$0.00	(w)		$0.00	(c)(w)		$0.00		$0.00			$0.00			$0.00
Net realized and unrealized gain (loss)		—			(0.00	)(w)		—		0.00	(w)		0.00	(w)		—
Total from investment operations		$0.00	(w)		$0.00	(w)		$0.00		$0.00	(w)		$0.00	(w)		$0.00
Less distributions declared to shareholders
From net investment income		$(0.00	)(w)		$(0.00	)(w)		$—		$—			$—			$—
Net asset value, end of period		$1.00			$1.00			$1.00		$1.00			$1.00			$1.00
Total return (%) (r)(t)		0.23	(n)		0.08	(c)		0.00		0.00	(w)		0.00	(w)		0.00
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.69	(a)		1.66	(c)		1.66		1.67			1.65			1.68
Expenses after expense reductions (f)		0.68	(a)		0.50	(c)		0.23		0.07			0.09			0.15
Net investment income (loss)		0.45	(a)		0.07	(c)		0.00		0.00			0.00			0.00
Net assets at end of period (000 omitted)		$8,910			$12,236			$14,569		$14,363			$16,819			$21,080

See Notes to Financial Statements

Financial Highlights – continued


	Six months ended 2/28/18			Year ended
Class R2	Six months ended 2/28/18			8/31/17			8/31/16		8/31/15			8/31/14			8/31/13
	(unaudited)
Net asset value, beginning of period		$1.00			$1.00			$1.00		$1.00			$1.00			$1.00
Income (loss) from investment operations
Net investment income (loss) (d)		$0.00	(w)		$0.00	(c)(w)		$0.00		$0.00			$0.00			$0.00
Net realized and unrealized gain (loss)		—			(0.00	)(w)		—		0.00	(w)		0.00	(w)		—
Total from investment operations		$0.00	(w)		$0.00	(w)		$0.00		$0.00	(w)		$0.00	(w)		$0.00
Less distributions declared to shareholders
From net investment income		$(0.00	)(w)		$(0.00	)(w)		$—		$—			$—			$—
Net asset value, end of period		$1.00			$1.00			$1.00		$1.00			$1.00			$1.00
Total return (%) (r)(t)		0.23	(n)		0.08	(c)		0.00		0.00	(w)		0.00	(w)		0.00
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.19	(a)		1.16	(c)		1.16		1.17			1.15			1.18
Expenses after expense reductions (f)		0.68	(a)		0.51	(c)		0.23		0.07			0.09			0.15
Net investment income (loss)		0.45	(a)		0.08	(c)		0.00		0.00			0.00			0.00
Net assets at end of period (000 omitted)		$37,967			$48,184			$51,537		$53,058			$57,634			$74,406

See Notes to Financial Statements

Financial Highlights – continued


	Six months ended 2/28/18			Year ended
Class R3	Six months ended 2/28/18			8/31/17			8/31/16		8/31/15			8/31/14			8/31/13
	(unaudited)
Net asset value, beginning of period		$1.00			$1.00			$1.00		$1.00			$1.00			$1.00
Income (loss) from investment operations
Net investment income (loss) (d)		$0.00	(w)		$0.00	(c)(w)		$0.00		$0.00			$0.00			$0.00
Net realized and unrealized gain (loss)		—			(0.00	)(w)		—		0.00	(w)		0.00	(w)		—
Total from investment operations		$0.00	(w)		$0.00	(w)		$0.00		$0.00	(w)		$0.00	(w)		$0.00
Less distributions declared to shareholders
From net investment income		$(0.00	)(w)		$(0.00	)(w)		$—		$—			$—			$—
Net asset value, end of period		$1.00			$1.00			$1.00		$1.00			$1.00			$1.00
Total return (%) (r)(t)		0.23	(n)		0.08	(c)		0.00		0.00	(w)		0.00	(w)		0.00
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		0.94	(a)		0.91	(c)		0.91		0.92			0.90			0.93
Expenses after expense reductions (f)		0.68	(a)		0.51	(c)		0.23		0.07			0.09			0.15
Net investment income (loss)		0.45	(a)		0.08	(c)		0.00		0.00			0.00			0.00
Net assets at end of period (000 omitted)		$30,556			$35,196			$37,650		$44,872			$53,916			$64,925

See Notes to Financial Statements

Financial Highlights – continued


	Six months ended 2/28/18			Year ended
Class R4	Six months ended 2/28/18			8/31/17			8/31/16		8/31/15			8/31/14			8/31/13
	(unaudited)
Net asset value, beginning of period		$1.00			$1.00			$1.00		$1.00			$1.00			$1.00
Income (loss) from investment operations
Net investment income (loss) (d)		$0.00	(w)		$0.00	(c)(w)		$0.00		$0.00			$0.00			$0.00
Net realized and unrealized gain (loss)		—			(0.00	)(w)		—		0.00	(w)		0.00	(w)		—
Total from investment operations		$0.00	(w)		$0.00	(w)		$0.00		$0.00	(w)		$0.00	(w)		$0.00
Less distributions declared to shareholders
From net investment income		$(0.00	)(w)		$(0.00	)(w)		$—		$—			$—			$—
Net asset value, end of period		$1.00			$1.00			$1.00		$1.00			$1.00			$1.00
Total return (%) (r)(t)		0.23	(n)		0.08	(c)		0.00		0.00	(w)		0.00	(w)		0.00
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		0.69	(a)		0.67	(c)		0.66		0.67			0.65			0.68
Expenses after expense reductions (f)		0.68	(a)		0.52	(c)		0.23		0.07			0.09			0.15
Net investment income (loss)		0.45	(a)		0.08	(c)		0.00		0.00			0.00			0.00
Net assets at end of period (000 omitted)		$2,708			$3,250			$3,077		$3,034			$2,907			$820

See Notes to Financial Statements

Financial Highlights – continued


	Six months ended 2/28/18			Year ended
Class 529A	Six months ended 2/28/18			8/31/17			8/31/16		8/31/15			8/31/14			8/31/13
	(unaudited)
Net asset value, beginning of period		$1.00			$1.00			$1.00		$1.00			$1.00			$1.00
Income (loss) from investment operations
Net investment income (loss) (d)		$0.00	(w)		$0.00	(c)(w)		$0.00		$0.00			$0.00			$0.00
Net realized and unrealized gain (loss)		—			(0.00	)(w)		—		0.00	(w)		0.00	(w)		—
Total from investment operations		$0.00	(w)		$0.00	(w)		$0.00		$0.00	(w)		$0.00	(w)		$0.00
Less distributions declared to shareholders
From net investment income		$(0.00	)(w)		$(0.00	)(w)		$—		$—			$—			$—
Net asset value, end of period		$1.00			$1.00			$1.00		$1.00			$1.00			$1.00
Total return (%) (r)(t)		0.20	(n)		0.06	(c)		0.00		0.00	(w)		0.00	(w)		0.00
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.02	(a)		1.01	(c)		1.00		1.02			1.00			1.03
Expenses after expense reductions (f)		0.73	(a)		0.53	(c)		0.23		0.07			0.09			0.15
Net investment income (loss)		0.41	(a)		0.06	(c)		0.00		0.00			0.00			0.00
Net assets at end of period (000 omitted)		$13,271			$13,208			$12,841		$11,383			$10,927			$10,897

See Notes to Financial Statements

Financial Highlights – continued


	Six months ended 2/28/18			Year ended
Class 529B	Six months ended 2/28/18			8/31/17			8/31/16		8/31/15			8/31/14			8/31/13
	(unaudited)
Net asset value, beginning of period		$1.00			$1.00			$1.00		$1.00			$1.00			$1.00
Income (loss) from investment operations
Net investment income (loss) (d)		$0.00	(w)		$0.00	(c)(w)		$0.00		$0.00			$0.00			$0.00
Net realized and unrealized gain (loss)		—			(0.00	)(w)		—		0.00	(w)		0.00	(w)		—
Total from investment operations		$0.00	(w)		$0.00	(w)		$0.00		$0.00	(w)		$0.00	(w)		$0.00
Less distributions declared to shareholders
From net investment income		$(0.00	)(w)		$(0.00	)(w)		$—		$—			$—			$—
Net asset value, end of period		$1.00			$1.00			$1.00		$1.00			$1.00			$1.00
Total return (%) (r)(t)		0.21	(n)		0.06	(c)		0.00		0.00	(w)		0.00	(w)		0.00
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.77	(a)		1.76	(c)		1.76		1.77			1.75			1.78
Expenses after expense reductions (f)		0.73	(a)		0.53	(c)		0.22		0.07			0.10			0.15
Net investment income (loss)		0.41	(a)		0.06	(c)		0.00		0.00			0.00			0.00
Net assets at end of period (000 omitted)		$329			$348			$355		$440			$531			$676

See Notes to Financial Statements

Financial Highlights – continued


	Six months ended 2/28/18			Year ended
Class 529C	Six months ended 2/28/18			8/31/17			8/31/16		8/31/15			8/31/14			8/31/13
	(unaudited)
Net asset value, beginning of period		$1.00			$1.00			$1.00		$1.00			$1.00			$1.00
Income (loss) from investment operations
Net investment income (loss) (d)		$0.00	(w)		$0.00	(c)(w)		$0.00		$0.00			$0.00			$0.00
Net realized and unrealized gain (loss)		—			(0.00	)(w)		—		0.00	(w)		0.00	(w)		—
Total from investment operations		$0.00	(w)		$0.00	(w)		$0.00		$0.00	(w)		$0.00	(w)		$0.00
Less distributions declared to shareholders
From net investment income		$(0.00	)(w)		$(0.00	)(w)		$—		$—			$—			$—
Net asset value, end of period		$1.00			$1.00			$1.00		$1.00			$1.00			$1.00
Total return (%) (r)(t)		0.21	(n)		0.06	(c)		0.00		0.00	(w)		0.00	(w)		0.00
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.77	(a)		1.76	(c)		1.76		1.77			1.75			1.78
Expenses after expense reductions (f)		0.73	(a)		0.54	(c)		0.24		0.07			0.09			0.15
Net investment income (loss)		0.41	(a)		0.06	(c)		0.00		0.00			0.00			0.00
Net assets at end of period (000 omitted)		$7,099			$6,957			$6,728		$5,866			$6,240			$6,072

(a)	Annualized.

(c)	Amount reflects a one-time reimbursement of expenses by the custodian (or former custodian) without which net investment income and performance would be lower and expenses would be higher.

(d)	Per share data is based on average shares outstanding.

(f)	Ratios do not reflect reductions from fees paid indirectly, if applicable.

(n)	Not annualized.

(r)	Certain expenses have been reduced without which performance would have been lower.

(t)	Total returns do not include any applicable sales charges.

(w)	Per share amount was less than $0.01 and total return or ratio was less than 0.01%, as applicable.

See Notes to Financial Statements

NOTES TO FINANCIAL STATEMENTS

(unaudited)

(1) Business and Organization

MFS U.S. Government Cash Reserve Fund (the fund) is a diversified series of MFS Series Trust I (the trust). The trust is organized as a Massachusetts business trust and is registered under the Investment Company Act of 1940, as amended, as an open-end management investment company.

(2) Significant Accounting Policies

Investment Valuations – Pursuant to procedures approved by the Board of Trustees, investments held by the fund are generally valued at amortized cost, which approximates market value. Amortized cost involves valuing an instrument at its cost as adjusted for amortization of premium or accretion of discount rather than its current market value. The amortized cost value of an instrument can be different from the market value of an instrument.

Notes to Financial Statements (unaudited) – continued

quoted prices in active markets for identical assets or liabilities. Level 2 includes other significant observable market-based inputs (including quoted prices for similar securities, interest rates, prepayment speed, and credit risk). Level 3 includes unobservable inputs, which may include the adviser’s own assumptions in determining the fair value of investments. The following is a summary of the levels used as of February 28, 2018 in valuing the fund’s assets or liabilities:


Investments at Value	Level 1		Level 2		Level 3		Total
Short-Term Securities		$—		$244,294,276		$—		$244,294,276

For further information regarding security characteristics, see the Portfolio of Investments.

Repurchase Agreements – The fund enters into repurchase agreements under the terms of Master Repurchase Agreements with approved counterparties. Each repurchase agreement is recorded at cost. The fund requires that the securities collateral in a repurchase transaction be transferred to a custodian. The fund monitors, on a daily basis, the value of the collateral to ensure that its value, including accrued interest, is greater than amounts owed to the fund under each such repurchase agreement. Upon an event of default under a Master Repurchase Agreement, the non-defaulting party may close out all transactions traded under such agreement and net amounts owed under each transaction to one net amount payable by one party to the other. Absent an event of default, the Master Repurchase Agreement does not result in an offset of reported amounts of assets and liabilities in the Statement of Assets and Liabilities across transactions between the fund and the applicable counterparty. The fund and other funds managed by MFS may utilize a joint trading account for the purpose of entering into one or more repurchase agreements. At February 28, 2018, the fund had investments in repurchase agreements with a gross value of $18,945,000 included in investments in unaffiliated issuers in the Statement of Assets and Liabilities. The value of the related collateral exceeded the value of the repurchase agreements at period end.

Investment Transactions and Income – Investment transactions are recorded on the trade date. Interest income is recorded on the accrual basis. All premium and discount is amortized or accreted for financial statement purposes in accordance with U.S. generally accepted accounting principles.

Notes to Financial Statements (unaudited) – continued

three year period. Management has analyzed the fund’s tax positions taken on federal and state tax returns for all open tax years and does not believe that there are any uncertain tax positions that require recognition of a tax liability.

During the six months ended February 28, 2018, there were no significant adjustments due to differences between book and tax accounting.


	Year ended 8/31/17
Ordinary income (including any short-term capital gains)		$227,426

The federal tax cost and the tax basis components of distributable earnings were as follows:


As of 2/28/18
Cost of investments	$244,294,276

As of 8/31/17
Post-October capital loss deferral	(5	)
Other temporary differences	(7,719	)

The aggregate cost above includes prior fiscal year end tax adjustments, if applicable.

Multiple Classes of Shares of Beneficial Interest – The fund offers multiple classes of shares, which differ in their respective distribution, service, and program manager fees. The fund’s income and common expenses are allocated to shareholders based on the value of settled shares outstanding of each class. The fund’s realized and unrealized gain (loss) are allocated to shareholders based on the daily net assets of each class. Dividends are declared separately for each class. Differences in per share dividend rates are generally due to differences in separate class expenses. Class B and Class 529B shares will convert to Class A and Class 529A shares, respectively, approximately eight years after purchase. Effective April 23, 2018, Class C and Class 529C shares will convert to Class A and Class 529A shares, respectively, approximately ten years after

Notes to Financial Statements (unaudited) – continued

purchase. The fund’s distributions declared to shareholders as reported in the Statements of Changes in Net Assets are presented by class as follows:


	From net investment income
	Six months ended 2/28/18		Year ended 8/31/17
Class A		$228,475		$89,813
Class B		35,918		14,501
Class C		80,681		31,490
Class R1		23,337		8,882
Class R2		97,358		39,425
Class R3		72,291		27,743
Class R4		6,892		2,601
Class 529A		26,272		8,383
Class 529B		636		214
Class 529C		14,174		4,374
Total		$586,034		$227,426

(3) Transactions with Affiliates

Investment Adviser – The fund has an investment advisory agreement with MFS to provide overall investment management and related administrative services and facilities to the fund. The management fee is computed daily and paid monthly at an annual rate of 0.40% of the fund’s average daily net assets.

MFS has also agreed in writing to reduce its management fee by a specified amount if certain MFS mutual fund assets exceed thresholds agreed to by MFS and the fund’s Board of Trustees. For the six months ended February 28, 2018, this management fee reduction amounted to $11,079, which is included in the reduction of total expenses in the Statement of Operations. The management fee incurred for the six months ended February 28, 2018 was equivalent to an annual effective rate of 0.39% of the fund’s average daily net assets.

Distributor – The Board of Trustees has adopted a distribution plan for certain share classes pursuant to Rule 12b-1 of the Investment Company Act of 1940.

The fund’s distribution plan provides that the fund will pay MFS Fund Distributors, Inc. (MFD), a wholly-owned subsidiary of MFS, for services provided by MFD and financial intermediaries in connection with the distribution and servicing of certain share classes. One component of the plan is a distribution fee paid to MFD and another component of the plan is a service fee paid to MFD. MFD may subsequently pay all, or a portion, of the distribution and/or service fees to financial intermediaries.

Notes to Financial Statements (unaudited) – continued

Distribution Plan Fee Table:


	Distribution Fee Rate (d)		Service Fee Rate (d)		Total Distribution Plan (d)		Annual Effective Rate (e)		Distribution and Service Fee
Class A		—		0.25%		0.25%		0.00%		$124,012
Class B		0.75%		0.25%		1.00%		0.00%		78,435
Class C		0.75%		0.25%		1.00%		0.00%		176,129
Class R1		0.75%		0.25%		1.00%		0.00%		51,748
Class R2		0.25%		0.25%		0.50%		0.00%		107,293
Class R3		—		0.25%		0.25%		0.00%		39,718
Class 529A		—		0.25%		0.25%		0.00%		16,007
Class 529B		0.75%		0.25%		1.00%		0.00%		1,559
Class 529C		0.75%		0.25%		1.00%		0.00%		34,456
Total Distribution and Service Fees										$629,357

(d)

(e)

The annual effective rates represent actual fees incurred under the distribution plan for the six months ended February 28, 2018 based on each class’s average daily net assets. MFD has agreed in writing to waive any distribution and/or service fees for Class A, Class B, Class C, Class R1, Class R2, Class R3, Class 529A, Class 529B, and Class 529C. This written agreement will continue until modified by the fund’s Board of Trustees, but such agreement will continue until at least December 31, 2018. These reductions, for the six-months ended February 28, 2018, for Class A, Class B, Class C, Class R1, Class R2, Class R3, Class 529A, Class 529B, and Class 529C amounted to $124,012, $78,435, $176,129, $51,748, $107,293, $39,718, $16,007, $1,559, and $34,456, respectively, and are included in the reduction of total expenses in the Statement of Operations.


	Amount
Class A		$76
Class B		24,145
Class C		2,308
Class 529B		—
Class 529C		589

Notes to Financial Statements (unaudited) – continued

waive a portion of this fee in an amount equal to 0.05% of the average daily net assets for each 529 share class. This waiver agreement terminated on December 10, 2017. For the period from September 1, 2017 through December 10, 2017, this waiver amounted to $2,854 and is included in the reduction of total expenses in the Statement of Operations. Effective December 11, 2017, the fund has entered into an agreement with MFD pursuant to which MFD receives an annual fee of up to 0.05% of the average daily net assets attributable to each 529 share class. The program manager fee incurred for the six months ended February 28, 2018 was equivalent to an annual effective rate of 0.05% of the average daily net assets attributable to each 529 share class. The services provided by MFD, or a third party with which MFD contracts, include recordkeeping and tax reporting and account services, as well as services designed to maintain the program’s compliance with the Internal Revenue Code and other regulatory requirements. Program manager fees and waivers for the six months ended February 28, 2018, were as follows:


	Fee		Waiver
Class 529A		$5,032		$1,830
Class 529B		123		46
Class 529C		2,701		978
Total Program Manager Fees and Waivers		$7,856		$2,854

Shareholder Servicing Agent – MFS Service Center, Inc. (MFSC), a wholly-owned subsidiary of MFS, receives a fee from the fund for its services as shareholder servicing agent calculated as a percentage of the average daily net assets of the fund as determined periodically under the supervision of the fund’s Board of Trustees. For the six months ended February 28, 2018, the fee was $78,452, which equated to 0.0608% annually of the fund’s average daily net assets. MFSC also receives payment from the fund for out-of-pocket expenses, sub-accounting and other shareholder servicing costs which may be paid to affiliated and unaffiliated service providers. For the six months ended February 28, 2018, these out-of-pocket expenses, sub-accounting and other shareholder servicing costs amounted to $158,656.

Prior to December 31, 2001, the fund had an unfunded defined benefit plan (“DB plan”) for independent Trustees. As of December 31, 2001, the Board took action

Notes to Financial Statements (unaudited) – continued

to terminate the DB plan with respect to then-current and any future independent Trustees, such that the DB plan covers only certain of those former independent Trustees who retired on or before December 31, 2001. The DB plan resulted in a pension expense of $708 and is included in “Independent Trustees’ compensation” in the Statement of Operations for the six months ended February 28, 2018. The liability for deferred retirement benefits payable to certain independent Trustees under the DB plan amounted to $5,813 at February 28, 2018, and is included in “Payable for independent Trustees’ compensation” in the Statement of Assets and Liabilities.

Other – This fund and certain other funds managed by MFS (the funds) have entered into a service agreement (the ISO Agreement) which provides for payment of fees solely by the funds to Tarantino LLC in return for the provision of services of an Independent Senior Officer (ISO) for the funds. Frank L. Tarantino serves as the ISO and is an officer of the funds and the sole member of Tarantino LLC. The funds can terminate the ISO Agreement with Tarantino LLC at any time under the terms of the ISO Agreement. For the six months ended February 28, 2018, the fee paid by the fund under this agreement was $234 and is included in “Miscellaneous” expense in the Statement of Operations. MFS has agreed to bear all expenses associated with office space, other administrative support, and supplies provided to the ISO.

At February 28, 2018, MFS held approximately 96% of the outstanding shares of Class R4.

(4) Shares of Beneficial Interest

The fund’s Declaration of Trust permits the Trustees to issue an unlimited number of full and fractional shares of beneficial interest. Transactions in fund shares were as follows:


	Six months ended 2/28/18				Year ended 8/31/17
	Shares		Amount		Shares		Amount
Shares sold
Class A		18,535,972		$18,535,971		52,201,068		$52,201,070
Class B		2,766,276		2,766,276		13,010,177		13,010,176
Class C		6,753,308		6,753,309		26,105,909		26,105,907
Class R1		1,385,359		1,385,359		3,907,819		3,907,819
Class R2		5,592,437		5,592,840		13,316,853		13,316,880
Class R3		6,220,496		6,220,645		14,110,795		14,110,795
Class R4		76,058		76,059		519,206		519,208
Class 529A		3,499,899		3,499,899		6,937,795		6,937,795
Class 529B		141,150		141,150		184,277		184,277
Class 529C		2,247,832		2,247,832		4,065,880		4,065,880
		47,218,787		$47,219,340		134,359,779		$134,359,807

Notes to Financial Statements (unaudited) – continued


	Six months ended 2/28/18						Year ended 8/31/17
	Shares			Amount			Shares			Amount
Shares issued to shareholders in reinvestment of distributions
Class A		220,823			$220,823			86,846			$86,846
Class B		34,040			34,040			13,834			13,834
Class C		78,431			78,431			30,644			30,644
Class R1		23,283			23,283			8,848			8,848
Class R2		97,761			97,358			39,453			39,425
Class R3		72,440			72,291			27,726			27,726
Class R4		6,757			6,757			2,602			2,601
Class 529A		26,082			26,082			8,300			8,300
Class 529B		628			628			212			212
Class 529C		14,035			14,035			4,316			4,316
		574,280			$573,728			222,781			$222,752

Shares reacquired
Class A		(29,611,543	)		$(29,611,543	)		(67,169,924	)		$(67,169,924	)
Class B		(5,425,961	)		(5,425,962	)		(13,780,498	)		(13,780,501	)
Class C		(12,377,865	)		(12,377,865	)		(36,431,544	)		(36,431,544	)
Class R1		(4,734,494	)		(4,734,494	)		(6,250,419	)		(6,250,419	)
Class R2		(15,910,875	)		(15,910,875	)		(16,707,622	)		(16,707,622	)
Class R3		(10,935,016	)		(10,935,016	)		(16,590,937	)		(16,590,937	)
Class R4		(625,085	)		(625,085	)		(349,153	)		(349,153	)
Class 529A		(3,465,829	)		(3,465,829	)		(6,577,379	)		(6,577,379	)
Class 529B		(160,418	)		(160,418	)		(192,320	)		(192,320	)
Class 529C		(2,120,111	)		(2,120,111	)		(3,840,984	)		(3,840,984	)
		(85,367,197	)		$(85,367,198	)		(167,890,780	)		$(167,890,783	)

Net change
Class A		(10,854,748	)		$(10,854,749	)		(14,882,010	)		$(14,882,008	)
Class B		(2,625,645	)		(2,625,646	)		(756,487	)		(756,491	)
Class C		(5,546,126	)		(5,546,125	)		(10,294,991	)		(10,294,993	)
Class R1		(3,325,852	)		(3,325,852	)		(2,333,752	)		(2,333,752	)
Class R2		(10,220,677	)		(10,220,677	)		(3,351,316	)		(3,351,317	)
Class R3		(4,642,080	)		(4,642,080	)		(2,452,416	)		(2,452,416	)
Class R4		(542,270	)		(542,269	)		172,655			172,656
Class 529A		60,152			60,152			368,716			368,716
Class 529B		(18,640	)		(18,640	)		(7,831	)		(7,831	)
Class 529C		141,756			141,756			229,212			229,212
		(37,574,130	)		$(37,574,130	)		(33,308,220	)		$(33,308,224	)

Notes to Financial Statements (unaudited) – continued

(5) Line of Credit

The fund and certain other funds managed by MFS participate in a $1.25 billion unsecured committed line of credit, subject to a $1 billion sublimit, provided by a syndication of banks under a credit agreement. Borrowings may be made for temporary financing needs. Interest is charged to each fund, based on its borrowings, generally at a rate equal to the higher of the Overnight Federal Reserve funds rate or daily one month LIBOR plus an agreed upon spread. A commitment fee, based on the average daily, unused portion of the committed line of credit, is allocated among the participating funds at the end of each calendar quarter. In addition, the fund and other funds managed by MFS have established unsecured uncommitted borrowing arrangements with certain banks for temporary financing needs. Interest is charged to each fund, based on its borrowings, at a rate equal to the Overnight Federal Reserve funds rate plus an agreed upon spread. For the six months ended February 28, 2018, the fund’s commitment fee and interest expense were $980 and $0, respectively, and are included in “Miscellaneous” expense in the Statement of Operations.

PROXY VOTING POLICIES AND INFORMATION

QUARTERLY PORTFOLIO DISCLOSURE

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100 F Street, NE, Room 1580

Washington, D.C. 20549

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INFORMATION ABOUT FUND CONTRACTS AND LEGAL CLAIMS

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CONTACT

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ACCOUNT SERVICE AND LITERATURE

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MAILING ADDRESS

MFS Service Center, Inc.

P.O. Box 55824

Boston, MA 02205-5824

OVERNIGHT MAIL

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Semiannual Report

February 28, 2018

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MFS® Value Fund

LOGO

EIF-SEM

MFS® Value Fund

CONTENTS


Letter from the Executive Chairman			1
Portfolio composition			2
Expense table			3
Portfolio of investments			5
Statement of assets and liabilities			10
Statement of operations			12
Statements of changes in net assets			13
Financial highlights			14
Notes to financial statements			27
Proxy voting policies and information			39
Quarterly portfolio disclosure			39
Further information			39
Information about fund contracts and legal claims			40
Provision of financial reports and summary prospectuses			40
Contact information back cover

The report is prepared for the general information of shareholders.

It is authorized for distribution to prospective investors only when preceded or accompanied by a current prospectus.

NOT FDIC INSURED • MAY LOSE VALUE • NO BANK GUARANTEE

LOGO

LETTER FROM THE EXECUTIVE CHAIRMAN

Dear Shareholders:

Rising bond yields have led to a measurable uptick in market volatility — a departure from the low-volatility environment that prevailed for much of 2017. In spite of this,

U.S. protectionism is also a growing concern, as investors fear that trade friction could disrupt the synchronized uptick in global growth.

Respectfully,

LOGO

Robert J. Manning

Executive Chairman

MFS Investment Management

April 13, 2018

The opinions expressed in this letter are subject to change and may not be relied upon for investment advice. No forecasts can be guaranteed.

PORTFOLIO COMPOSITION

Portfolio structure

LOGO


Top ten holdings
JPMorgan Chase & Co.			5.0%
Wells Fargo & Co.			3.4%
Johnson & Johnson			3.4%
Philip Morris International, Inc.			3.1%
Accenture PLC, “A”			2.9%
Goldman Sachs Group, Inc.			2.6%
Citigroup, Inc.			2.4%
U.S. Bancorp			2.3%
Medtronic PLC			2.2%
Pfizer, Inc.			2.2%


Equity sectors
Financial Services			31.3%
Health Care			15.2%
Consumer Staples			11.3%
Industrial Goods & Services			9.9%
Special Products & Services			6.3%
Energy			4.9%
Leisure			4.7%
Basic Materials			4.4%
Utilities & Communications			3.0%
Autos & Housing			2.5%
Technology			2.1%
Transportation			2.0%
Retailing			0.6%

Percentages are based on net assets as of February 28, 2018.

The portfolio is actively managed and current holdings may be different.

EXPENSE TABLE

Fund expenses borne by the shareholders during the period, September 1, 2017 through February 28, 2018

The example is based on an investment of $1,000 invested at the beginning of the period and held for the entire period September 1, 2017 through February 28, 2018.

Actual Expenses

Hypothetical Example for Comparison Purposes

Expense Table – continued


Share Class		Annualized Expense Ratio		Beginning Account Value 9/01/17		Ending Account Value 2/28/18		Expenses Paid During Period (p) 9/01/17-2/28/18
A	Actual		0.81%		$1,000.00		$1,075.81		$4.17
A	Hypothetical (h)		0.81%		$1,000.00		$1,020.78		$4.06
B	Actual		1.56%		$1,000.00		$1,071.91		$8.01
B	Hypothetical (h)		1.56%		$1,000.00		$1,017.06		$7.80
C	Actual		1.56%		$1,000.00		$1,071.73		$8.01
C	Hypothetical (h)		1.56%		$1,000.00		$1,017.06		$7.80
I	Actual		0.56%		$1,000.00		$1,077.07		$2.88
I	Hypothetical (h)		0.56%		$1,000.00		$1,022.02		$2.81
R1	Actual		1.56%		$1,000.00		$1,071.80		$8.01
R1	Hypothetical (h)		1.56%		$1,000.00		$1,017.06		$7.80
R2	Actual		1.06%		$1,000.00		$1,074.66		$5.45
R2	Hypothetical (h)		1.06%		$1,000.00		$1,019.54		$5.31
R3	Actual		0.81%		$1,000.00		$1,075.93		$4.17
R3	Hypothetical (h)		0.81%		$1,000.00		$1,020.78		$4.06
R4	Actual		0.56%		$1,000.00		$1,077.26		$2.88
R4	Hypothetical (h)		0.56%		$1,000.00		$1,022.02		$2.81
R6	Actual		0.47%		$1,000.00		$1,077.82		$2.42
R6	Hypothetical (h)		0.47%		$1,000.00		$1,022.46		$2.36
529A	Actual		0.83%		$1,000.00		$1,075.87		$4.27
529A	Hypothetical (h)		0.83%		$1,000.00		$1,020.68		$4.16
529B	Actual		1.61%		$1,000.00		$1,071.84		$8.27
529B	Hypothetical (h)		1.61%		$1,000.00		$1,016.81		$8.05
529C	Actual		1.60%		$1,000.00		$1,071.68		$8.22
529C	Hypothetical (h)		1.60%		$1,000.00		$1,016.86		$8.00

(h)	5% class return per year before expenses.

(p)

Notes to Expense Table

Each class with a Rule 12b-1 service fee is subject to a rebate of a portion of such fee. Such rebates are included in the expense ratios above. For Class 529A, Class 529B, and Class 529C shares, this rebate reduced the expense ratios above by 0.03%, 0.01%, and 0.01%, respectively. See Note 3 in the Notes to Financial Statements for additional information.

PORTFOLIO OF INVESTMENTS

2/28/18 (unaudited)

The Portfolio of Investments is a complete list of all securities owned by your fund. It is categorized by broad-based asset classes.


Common Stocks - 98.2%
Issuer	Shares/Par		Value ($)
Aerospace - 5.5%
Honeywell International, Inc.		6,121,468	$	925,015,030
Lockheed Martin Corp.		961,860		338,997,938
Northrop Grumman Corp.		2,268,028		793,900,521
United Technologies Corp.		4,399,121		592,737,564

			$	2,650,651,053
Alcoholic Beverages - 1.1%
Diageo PLC		16,093,943	$	545,050,419

Apparel Manufacturers - 0.7%
Hanesbrands, Inc.		10,393,064	$	201,625,441
NIKE, Inc., “B”		1,693,459		113,512,557

			$	315,137,998
Automotive - 1.0%
Aptiv PLC		4,322,805	$	394,801,780
Delphi Technologies PLC		165,753		7,914,706
Harley-Davidson, Inc.		1,524,366		69,175,729

			$	471,892,215
Broadcasting - 2.0%
Interpublic Group of Companies, Inc.		15,801,462	$	369,754,211
Omnicom Group, Inc.		7,797,346		594,391,685

			$	964,145,896
Brokerage & Asset Managers - 3.0%
BlackRock, Inc.		1,056,383	$	580,408,512
Franklin Resources, Inc.		4,001,449		154,736,033
NASDAQ, Inc.		5,919,512		478,000,594
T. Rowe Price Group, Inc.		2,195,617		245,689,542

			$	1,458,834,681
Business Services - 6.3%
Accenture PLC, “A”		8,704,708	$	1,401,545,035
Amdocs Ltd.		1,762,009		115,922,572
Cognizant Technology Solutions Corp., “A”		1,926,241		157,990,287
DXC Technology Co.		2,491,038		255,431,036
Equifax, Inc.		2,164,291		244,564,883
Fidelity National Information Services, Inc.		5,161,037		501,549,576
Fiserv, Inc. (a)		2,584,434		370,581,991

			$	3,047,585,380

Portfolio of Investments (unaudited) – continued


Issuer	Shares/Par		Value ($)
Common Stocks - continued
Cable TV - 1.7%
Comcast Corp., “A”		21,879,759	$	792,266,073

Chemicals - 4.0%
3M Co.		2,704,389	$	636,910,653
DowDuPont, Inc.		2,779,575		195,404,123
Monsanto Co.		1,496,728		184,651,333
PPG Industries, Inc.		7,989,586		898,349,050

			$	1,915,315,159
Computer Software - Systems - 0.3%
International Business Machines Corp.		888,856	$	138,510,430

Construction - 1.5%
Sherwin-Williams Co.		1,035,238	$	415,730,876
Stanley Black & Decker, Inc.		1,843,192		293,417,735

			$	709,148,611
Consumer Products - 1.7%
Coty, Inc., “A”		9,742,402	$	188,223,206
Kimberly-Clark Corp.		862,021		95,615,369
Newell Brands, Inc.		4,702,165		120,798,619
Procter & Gamble Co.		2,564,136		201,335,959
Reckitt Benckiser Group PLC		2,825,688		224,029,527

			$	830,002,680
Containers - 0.4%
Crown Holdings, Inc. (a)		3,756,588	$	187,228,346

Electrical Equipment - 1.9%
HD Supply Holdings, Inc. (a)		2,355,390	$	85,382,888
Johnson Controls International PLC		23,048,754		849,807,560

			$	935,190,448
Electronics - 1.8%
Analog Devices, Inc.		1,372,143	$	123,698,691
Texas Instruments, Inc.		6,700,268		725,974,038

			$	849,672,729
Energy - Independent - 1.7%
EOG Resources, Inc.		4,846,307	$	491,512,456
Occidental Petroleum Corp.		5,107,063		335,023,333

			$	826,535,789

Portfolio of Investments (unaudited) – continued


Issuer	Shares/Par		Value ($)
Common Stocks - continued
Energy - Integrated - 1.5%
Chevron Corp.		3,376,102	$	377,853,336
Exxon Mobil Corp.		4,831,295		365,922,283

			$	743,775,619
Entertainment - 0.2%
Time Warner, Inc.		881,605	$	81,954,001

Food & Beverages - 4.6%
Archer Daniels Midland Co.		5,936,542	$	246,485,224
Danone S.A.		2,793,519		222,878,843
General Mills, Inc.		11,477,210		580,172,965
J.M. Smucker Co.		1,718,144		217,001,587
Nestle S.A.		9,178,636		730,620,806
PepsiCo, Inc.		2,128,259		233,533,860

			$	2,230,693,285
Health Maintenance Organizations - 0.8%
Cigna Corp.		1,945,524	$	381,108,696

Insurance - 7.4%
Aon PLC		6,151,150	$	863,129,368
Chubb Ltd.		6,347,245		900,801,010
MetLife, Inc.		11,297,746		521,842,888
Prudential Financial, Inc.		2,526,482		268,615,566
Travelers Cos., Inc.		7,060,004		981,340,556

			$	3,535,729,388
Leisure & Toys - 0.2%
Hasbro, Inc.		1,016,886	$	97,183,795

Machinery & Tools - 2.5%
Eaton Corp. PLC		5,964,731	$	481,353,792
Illinois Tool Works, Inc.		2,748,785		443,763,851
Ingersoll-Rand Co. Ltd., “A”		3,023,663		268,501,274

			$	1,193,618,917
Major Banks - 14.8%
Bank of New York Mellon Corp.		9,928,196	$	566,205,018
Goldman Sachs Group, Inc.		4,819,767		1,267,261,337
JPMorgan Chase & Co.		20,664,631		2,386,764,881
PNC Financial Services Group, Inc.		5,024,614		792,180,643
State Street Corp.		4,447,063		472,055,738
Wells Fargo & Co.		27,792,081		1,623,335,451

			$	7,107,803,068

Portfolio of Investments (unaudited) – continued


Issuer	Shares/Par		Value ($)
Common Stocks - continued
Medical & Health Technology & Services - 1.4%
CVS Health Corp.		1,159,220	$	78,513,971
Express Scripts Holding Co. (a)		3,224,591		243,295,391
McKesson Corp.		2,280,763		340,358,262

			$	662,167,624
Medical Equipment - 6.3%
Abbott Laboratories		10,507,029	$	633,889,059
Danaher Corp.		6,418,023		627,554,289
Medtronic PLC		13,489,362		1,077,665,130
Thermo Fisher Scientific, Inc.		3,228,565		673,414,088

			$	3,012,522,566
Oil Services - 1.7%
Schlumberger Ltd.		12,167,270	$	798,659,603

Other Banks & Diversified Financials - 5.8%
American Express Co.		5,293,329	$	516,152,511
Citigroup, Inc.		15,388,406		1,161,670,769
U.S. Bancorp		20,063,740		1,090,664,906

			$	2,768,488,186
Pharmaceuticals - 6.7%
Johnson & Johnson		12,474,905	$	1,620,240,662
Merck & Co., Inc.		6,787,479		368,017,111
Novartis AG		1,319,108		110,366,393
Pfizer, Inc.		28,918,478		1,050,029,936
Roche Holding AG		378,477		87,756,951

			$	3,236,411,053
Printing & Publishing - 0.7%
Moody’s Corp.		2,063,309	$	344,325,006

Railroad & Shipping - 1.5%
Canadian National Railway Co.		3,306,188	$	255,799,765
Union Pacific Corp.		3,655,291		476,101,653

			$	731,901,418
Real Estate - 0.3%
Public Storage, Inc., REIT		854,593	$	166,167,063

Telephone Services - 0.7%
Verizon Communications, Inc.		7,213,848	$	344,389,104

Portfolio of Investments (unaudited) – continued


Issuer	Shares/Par		Value ($)
Common Stocks - continued
Tobacco - 3.8%
Altria Group, Inc.		5,424,557	$	341,475,863
Philip Morris International, Inc.		14,205,716		1,471,001,892

			$	1,812,477,755
Trucking - 0.5%
United Parcel Service, Inc., “B”		2,438,855	$	254,640,851

Utilities - Electric Power - 2.2%
Duke Energy Corp.		8,325,428	$	627,237,746
Southern Co.		6,342,608		273,112,700
Xcel Energy, Inc.		4,103,377		177,594,157

			$	1,077,944,603
Total Common Stocks (Identified Cost, $29,735,380,673)			$	47,219,129,508

Investment Companies (h) - 1.5%
Money Market Funds - 1.5%
MFS Institutional Money Market Portfolio, 1.52% (v) (Identified Cost, $732,069,344)		732,155,167	$	732,081,951

Other Assets, Less Liabilities - 0.3%				121,381,432
Net Assets - 100.0%			$	48,072,592,891

(a)	Non-income producing security.

(h)

(v)	Affiliated issuer that is available only to investment companies managed by MFS. The rate quoted for the MFS Institutional Money Market Portfolio is the annualized seven-day yield of the fund at period end.

The following abbreviations are used in this report and are defined:

PLC

Public Limited Company

REIT

Real Estate Investment Trust

See Notes to Financial Statements

Financial Statements

STATEMENT OF ASSETS AND LIABILITIES

At 2/28/18 (unaudited)

This statement represents your fund’s balance sheet, which details the assets and liabilities comprising the total value of the fund.


Assets
Investments in unaffiliated issuers, at value (identified cost, $29,735,380,673)			$47,219,129,508
Investments in affiliated issuers, at value (identified cost, $732,069,344)			732,081,951
Receivables for
Investments sold			605,953
Fund shares sold			96,052,668
Dividends			123,717,625
Other assets			149,329
Total assets			$48,171,737,034
Liabilities
Payables for
Investments purchased			$18,522,423
Fund shares reacquired			69,092,813
Payable to affiliates
Investment adviser			1,202,037
Shareholder servicing costs			9,356,196
Distribution and service fees			213,729
Program manager fee			88
Payable for independent Trustees’ compensation			3,907
Accrued expenses and other liabilities			752,950
Total liabilities			$99,144,143
Net assets			$48,072,592,891
Net assets consist of
Paid-in capital			$30,057,105,490
Unrealized appreciation (depreciation)			17,484,196,133
Accumulated net realized gain (loss)			422,729,537
Undistributed net investment income			108,561,731
Net assets			$48,072,592,891
Shares of beneficial interest outstanding			1,185,976,175

Statement of Assets and Liabilities (unaudited) – continued


	Net assets		Shares outstanding		Net asset value per share (a)
Class A		$6,303,866,029		155,798,220		$40.46
Class B		128,243,051		3,188,275		40.22
Class C		1,397,449,381		34,978,390		39.95
Class I		20,983,531,972		515,659,181		40.69
Class R1		27,651,399		697,206		39.66
Class R2		595,010,755		14,861,499		40.04
Class R3		2,286,837,749		56,740,821		40.30
Class R4		3,314,936,004		81,923,584		40.46
Class R6		13,003,682,605		321,344,072		40.47
Class 529A		24,244,590		604,145		40.13
Class 529B		962,502		24,276		39.65
Class 529C		6,176,854		156,506		39.47

(a)

Maximum offering price per share was equal to the net asset value per share for all share classes, except for Classes A and 529A, for which the maximum offering prices per share were $42.93 [100 / 94.25 x $40.46] and $42.58 [100 / 94.25 x $40.13], respectively. On sales of $50,000 or more, the maximum offering prices of Class A and Class 529A shares are reduced. A contingent deferred sales charge may be imposed on redemptions of Class A, Class B, Class C, Class 529B, and Class 529C shares. Redemption price per share was equal to the net asset value per share for Classes I, R1, R2, R3, R4, R6, and 529A. Net asset value per share is calculated using actual net assets and shares outstanding rather than amounts that have been rounded for presentation purposes.

See Notes to Financial Statements

Financial Statements

STATEMENT OF OPERATIONS

Six months ended 2/28/18 (unaudited)

This statement describes how much your fund earned in investment income and accrued in expenses. It also describes any gains and/or losses generated by fund operations.


Net investment income (loss)
Income
Dividends	$494,738,038
Dividends from affiliated issuers	3,846,853
Income on securities loaned	827
Foreign taxes withheld	(319,810	)
Total investment income	$498,265,908
Expenses
Management fee	$107,071,088
Distribution and service fees	20,196,482
Shareholder servicing costs	17,828,672
Program manager fees	11,911
Administrative services fee	309,131
Independent Trustees’ compensation	111,845
Custodian fee	303,423
Shareholder communications	775,725
Audit and tax fees	35,192
Legal fees	229,378
Miscellaneous	934,631
Total expenses	$147,807,478
Reduction of expenses by investment adviser and distributor	(2,067,076	)
Net expenses	$145,740,402
Net investment income (loss)	$352,525,506
Realized and unrealized gain (loss)
Realized gain (loss) (identified cost basis)
Unaffiliated issuers	$1,017,829,161
Affiliated issuers	34,492
Foreign currency	131,535
Net realized gain (loss)	$1,017,995,188
Change in unrealized appreciation (depreciation)
Unaffiliated issuers	$2,023,212,382
Affiliated issuers	(9,973	)
Translation of assets and liabilities in foreign currencies	211,695
Net unrealized gain (loss)	$2,023,414,104
Net realized and unrealized gain (loss)	$3,041,409,292
Change in net assets from operations	$3,393,934,798

See Notes to Financial Statements

Financial Statements

STATEMENTS OF CHANGES IN NET ASSETS

These statements describe the increases and/or decreases in net assets resulting from operations, any distributions, and any shareholder transactions.


Change in net assets	Six months ended 2/28/18 (unaudited)			Year ended 8/31/17
From operations
Net investment income (loss)		$352,525,506			$791,181,918
Net realized gain (loss)		1,017,995,188			1,357,333,141
Net unrealized gain (loss)		2,023,414,104			2,727,155,783
Change in net assets from operations		$3,393,934,798			$4,875,670,842
Distributions declared to shareholders
From net investment income		$(377,663,226	)		$(767,688,873	)
From net realized gain		(1,378,787,000	)		(686,739,618	)
Total distributions declared to shareholders		$(1,756,450,226	)		$(1,454,428,491	)
Change in net assets from fund share transactions		$2,220,412,089			$955,436,745
Total change in net assets		$3,857,896,661			$4,376,679,096
Net assets
At beginning of period		44,214,696,230			39,838,017,134
At end of period (including undistributed net investment income of $108,561,731 and $133,699,451, respectively)		$48,072,592,891			$44,214,696,230

See Notes to Financial Statements

Financial Statements

FINANCIAL HIGHLIGHTS


	Six months ended 2/28/18			Year ended
Class A	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14			8/31/13
	(unaudited)
Net asset value, beginning of period		$39.00			$35.93			$33.38			$34.70			$29.81			$24.90
Income (loss) from investment operations
Net investment income (loss) (d)		$0.27			$0.66	(c)		$0.54			$0.63			$0.69			$0.50
Net realized and unrealized gain (loss)		2.69			3.65			3.81			(0.36	)		5.41			5.08
Total from investment operations		$2.96			$4.31			$4.35			$0.27			$6.10			$5.58
Less distributions declared to shareholders
From net investment income		$(0.29	)		$(0.62	)		$(0.56	)		$(0.67	)		$(0.63	)		$(0.48	)
From net realized gain		(1.21	)		(0.62	)		(1.24	)		(0.92	)		(0.58	)		(0.19	)
Total distributions declared to shareholders		$(1.50	)		$(1.24	)		$(1.80	)		$(1.59	)		$(1.21	)		$(0.67	)
Net asset value, end of period (x)		$40.46			$39.00			$35.93			$33.38			$34.70			$29.81
Total return (%) (r)(s)(t)(x)		7.58	(n)		12.24	(c)		13.55			0.68			20.78			22.75
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		0.82	(a)		0.86	(c)		0.90			0.90			0.90			0.93
Expenses after expense reductions (f)		0.81	(a)		0.84	(c)		0.86			0.86			0.88			0.92
Net investment income (loss)		1.32	(a)		1.77	(c)		1.60			1.80			2.10			1.80
Portfolio turnover		7	(n)		14			12			12			13			12
Net assets at end of period (000 omitted)		$6,303,866			$6,344,965			$9,033,842			$8,478,761			$9,448,535			$8,058,858

See Notes to Financial Statements

Financial Highlights – continued


	Six months ended 2/28/18			Year ended
Class B	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14			8/31/13
	(unaudited)
Net asset value, beginning of period		$38.76			$35.72			$33.19			$34.50			$29.64			$24.76
Income (loss) from investment operations
Net investment income (loss) (d)		$0.11			$0.37	(c)		$0.28			$0.37			$0.44			$0.29
Net realized and unrealized gain (loss)		2.69			3.64			3.79			(0.35	)		5.38			5.05
Total from investment operations		$2.80			$4.01			$4.07			$0.02			$5.82			$5.34
Less distributions declared to shareholders
From net investment income		$(0.13	)		$(0.35	)		$(0.30	)		$(0.41	)		$(0.38	)		$(0.27	)
From net realized gain		(1.21	)		(0.62	)		(1.24	)		(0.92	)		(0.58	)		(0.19	)
Total distributions declared to shareholders		$(1.34	)		$(0.97	)		$(1.54	)		$(1.33	)		$(0.96	)		$(0.46	)
Net asset value, end of period (x)		$40.22			$38.76			$35.72			$33.19			$34.50			$29.64
Total return (%) (r)(s)(t)(x)		7.19	(n)		11.40	(c)		12.68			(0.06	)		19.89			21.82
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.57	(a)		1.61	(c)		1.65			1.65			1.65			1.68
Expenses after expense reductions (f)		1.56	(a)		1.59	(c)		1.61			1.61			1.63			1.67
Net investment income (loss)		0.57	(a)		0.99	(c)		0.85			1.05			1.35			1.05
Portfolio turnover		7	(n)		14			12			12			13			12
Net assets at end of period (000 omitted)		$128,243			$137,361			$154,742			$154,205			$179,284			$169,208

See Notes to Financial Statements

Financial Highlights – continued


	Six months ended 2/28/18			Year ended
Class C	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14			8/31/13
	(unaudited)
Net asset value, beginning of period		$38.52			$35.50			$33.00			$34.33			$29.50			$24.65
Income (loss) from investment operations
Net investment income (loss) (d)		$0.11			$0.37	(c)		$0.28			$0.37			$0.44			$0.29
Net realized and unrealized gain (loss)		2.66			3.62			3.77			(0.36	)		5.36			5.03
Total from investment operations		$2.77			$3.99			$4.05			$0.01			$5.80			$5.32
Less distributions declared to shareholders
From net investment income		$(0.13	)		$(0.35	)		$(0.31	)		$(0.42	)		$(0.39	)		$(0.28	)
From net realized gain		(1.21	)		(0.62	)		(1.24	)		(0.92	)		(0.58	)		(0.19	)
Total distributions declared to shareholders		$(1.34	)		$(0.97	)		$(1.55	)		$(1.34	)		$(0.97	)		$(0.47	)
Net asset value, end of period (x)		$39.95			$38.52			$35.50			$33.00			$34.33			$29.50
Total return (%) (r)(s)(t)(x)		7.17	(n)		11.43	(c)		12.69			(0.09	)		19.92			21.83
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.57	(a)		1.61	(c)		1.65			1.65			1.65			1.68
Expenses after expense reductions (f)		1.56	(a)		1.59	(c)		1.61			1.61			1.63			1.67
Net investment income (loss)		0.57	(a)		0.99	(c)		0.85			1.06			1.35			1.05
Portfolio turnover		7	(n)		14			12			12			13			12
Net assets at end of period (000 omitted)		$1,397,449			$1,389,685			$1,538,605			$1,335,968			$1,359,860			$1,090,690

See Notes to Financial Statements

Financial Highlights – continued


	Six months ended 2/28/18			Year ended
Class I	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14			8/31/13
	(unaudited)
Net asset value, beginning of period		$39.22			$36.13			$33.56			$34.88			$29.96			$25.02
Income (loss) from investment operations
Net investment income (loss) (d)		$0.32			$0.74	(c)		$0.63			$0.72			$0.78			$0.57
Net realized and unrealized gain (loss)		2.70			3.70			3.82			(0.36	)		5.43			5.10
Total from investment operations		$3.02			$4.44			$4.45			$0.36			$6.21			$5.67
Less distributions declared to shareholders
From net investment income		$(0.34	)		$(0.73	)		$(0.64	)		$(0.76	)		$(0.71	)		$(0.54	)
From net realized gain		(1.21	)		(0.62	)		(1.24	)		(0.92	)		(0.58	)		(0.19	)
Total distributions declared to shareholders		$(1.55	)		$(1.35	)		$(1.88	)		$(1.68	)		$(1.29	)		$(0.73	)
Net asset value, end of period (x)		$40.69			$39.22			$36.13			$33.56			$34.88			$29.96
Total return (%) (r)(s)(t)(x)		7.71	(n)		12.54	(c)		13.83			0.93			21.07			23.06
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		0.57	(a)		0.61	(c)		0.65			0.65			0.65			0.68
Expenses after expense reductions (f)		0.56	(a)		0.59	(c)		0.61			0.61			0.63			0.67
Net investment income (loss)		1.57	(a)		1.98	(c)		1.84			2.06			2.35			2.05
Portfolio turnover		7	(n)		14			12			12			13			12
Net assets at end of period (000 omitted)		$20,983,532			$19,624,016			$17,134,836			$13,888,395			$13,905,910			$10,568,573

See Notes to Financial Statements

Financial Highlights – continued


	Six months ended 2/28/18			Year ended
Class R1	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14			8/31/13
	(unaudited)
Net asset value, beginning of period		$38.25			$35.27			$32.79			$34.11			$29.32			$24.50
Income (loss) from investment operations
Net investment income (loss) (d)		$0.11			$0.36	(c)		$0.28			$0.36			$0.43			$0.29
Net realized and unrealized gain (loss)		2.64			3.60			3.74			(0.34	)		5.33			5.00
Total from investment operations		$2.75			$3.96			$4.02			$0.02			$5.76			$5.29
Less distributions declared to shareholders
From net investment income		$(0.13	)		$(0.36	)		$(0.30	)		$(0.42	)		$(0.39	)		$(0.28	)
From net realized gain		(1.21	)		(0.62	)		(1.24	)		(0.92	)		(0.58	)		(0.19	)
Total distributions declared to shareholders		$(1.34	)		$(0.98	)		$(1.54	)		$(1.34	)		$(0.97	)		$(0.47	)
Net asset value, end of period (x)		$39.66			$38.25			$35.27			$32.79			$34.11			$29.32
Total return (%) (r)(s)(t)(x)		7.18	(n)		11.40(c	)		12.69			(0.07	)		19.88			21.83
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.57	(a)		1.61	(c)		1.65			1.65			1.65			1.68
Expenses after expense reductions (f)		1.56	(a)		1.59	(c)		1.61			1.61			1.63			1.67
Net investment income (loss)		0.57	(a)		0.99	(c)		0.85			1.06			1.33			1.06
Portfolio turnover		7	(n)		14			12			12			13			12
Net assets at end of period (000 omitted)		$27,651			$26,663			$27,096			$27,860			$33,390			$33,485

See Notes to Financial Statements

Financial Highlights – continued


	Six months ended 2/28/18			Year ended
Class R2	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14			8/31/13
	(unaudited)
Net asset value, beginning of period		$38.60			$35.59			$33.08			$34.40			$29.56			$24.69
Income (loss) from investment operations
Net investment income (loss) (d)		$0.21			$0.55	(c)		$0.45			$0.54			$0.60			$0.43
Net realized and unrealized gain (loss)		2.68			3.62			3.78			(0.35	)		5.36			5.04
Total from investment operations		$2.89			$4.17			$4.23			$0.19			$5.96			$5.47
Less distributions declared to shareholders
From net investment income		$(0.24	)		$(0.54	)		$(0.48	)		$(0.59	)		$(0.54	)		$(0.41	)
From net realized gain		(1.21	)		(0.62	)		(1.24	)		(0.92	)		(0.58	)		(0.19	)
Total distributions declared to shareholders		$(1.45	)		$(1.16	)		$(1.72	)		$(1.51	)		$(1.12	)		$(0.60	)
Net asset value, end of period (x)		$40.04			$38.60			$35.59			$33.08			$34.40			$29.56
Total return (%) (r)(s)(t)(x)		7.47	(n)		11.95	(c)		13.27			0.43			20.48			22.47
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.07	(a)		1.11	(c)		1.15			1.15			1.15			1.18
Expenses after expense reductions (f)		1.06	(a)		1.09	(c)		1.11			1.11			1.13			1.17
Net investment income (loss)		1.07	(a)		1.49	(c)		1.35			1.54			1.84			1.55
Portfolio turnover		7	(n)		14			12			12			13			12
Net assets at end of period (000 omitted)		$595,011			$614,044			$567,665			$521,592			$607,340			$572,590

See Notes to Financial Statements

Financial Highlights – continued


	Six months ended 2/28/18			Year ended
Class R3	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14			8/31/13
	(unaudited)
Net asset value, beginning of period		$38.85			$35.81			$33.28			$34.60			$29.73			$24.83
Income (loss) from investment operations
Net investment income (loss) (d)		$0.27			$0.65	(c)		$0.54			$0.63			$0.69			$0.50
Net realized and unrealized gain (loss)		2.68			3.64			3.79			(0.35	)		5.39			5.07
Total from investment operations		$2.95			$4.29			$4.33			$0.28			$6.08			$5.57
Less distributions declared to shareholders
From net investment income		$(0.29	)		$(0.63	)		$(0.56	)		$(0.68	)		$(0.63	)		$(0.48	)
From net realized gain		(1.21	)		(0.62	)		(1.24	)		(0.92	)		(0.58	)		(0.19	)
Total distributions declared to shareholders		$(1.50	)		$(1.25	)		$(1.80	)		$(1.60	)		$(1.21	)		$(0.67	)
Net asset value, end of period (x)		$40.30			$38.85			$35.81			$33.28			$34.60			$29.73
Total return (%) (r)(s)(t)(x)		7.59	(n)		12.23	(c)		13.54			0.69			20.77			22.77
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		0.82	(a)		0.86	(c)		0.90			0.90			0.90			0.93
Expenses after expense reductions (f)		0.81	(a)		0.84	(c)		0.86			0.86			0.87			0.91
Net investment income (loss)		1.32	(a)		1.74	(c)		1.60			1.80			2.11			1.80
Portfolio turnover		7	(n)		14			12			12			13			12
Net assets at end of period (000 omitted)		$2,286,838			$2,030,023			$1,903,910			$1,571,281			$1,559,863			$1,299,126

See Notes to Financial Statements

Financial Highlights – continued


	Six months ended 2/28/18			Year ended
Class R4	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14			8/31/13
	(unaudited)
Net asset value, beginning of period		$39.00			$35.94			$33.40			$34.72			$29.82			$24.90
Income (loss) from investment operations
Net investment income (loss) (d)		$0.32			$0.74	(c)		$0.62			$0.72			$0.77			$0.57
Net realized and unrealized gain (loss)		2.69			3.67			3.80			(0.36	)		5.42			5.08
Total from investment operations		$3.01			$4.41			$4.42			$0.36			$6.19			$5.65
Less distributions declared to shareholders
From net investment income		$(0.34	)		$(0.73	)		$(0.64	)		$(0.76	)		$(0.71	)		$(0.54	)
From net realized gain		(1.21	)		(0.62	)		(1.24	)		(0.92	)		(0.58	)		(0.19	)
Total distributions declared to shareholders		$(1.55	)		$(1.35	)		$(1.88	)		$(1.68	)		$(1.29	)		$(0.73	)
Net asset value, end of period (x)		$40.46			$39.00			$35.94			$33.40			$34.72			$29.82
Total return (%) (r)(s)(t)(x)		7.73	(n)		12.52	(c)		13.80			0.93			21.11			23.09
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		0.57	(a)		0.61	(c)		0.65			0.65			0.65			0.68
Expenses after expense reductions (f)		0.56	(a)		0.59	(c)		0.61			0.61			0.63			0.67
Net investment income (loss)		1.57	(a)		1.99	(c)		1.85			2.05			2.34			2.07
Portfolio turnover		7	(n)		14			12			12			13			12
Net assets at end of period (000 omitted)		$3,314,936			$3,060,883			$3,233,421			$2,787,041			$3,283,133			$2,892,340

See Notes to Financial Statements

Financial Highlights – continued


	Six months ended 2/28/18			Year ended
Class R6	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14			8/31/13
	(unaudited)
Net asset value, beginning of period		$39.01			$35.94			$33.40			$34.72			$29.82			$24.90
Income (loss) from investment operations
Net investment income (loss) (d)		$0.34			$0.76	(c)		$0.66			$0.76			$0.82			$0.60
Net realized and unrealized gain (loss)		2.69			3.69			3.80			(0.36	)		5.40			5.07
Total from investment operations		$3.03			$4.45			$4.46			$0.40			$6.22			$5.67
Less distributions declared to shareholders
From net investment income		$(0.36	)		$(0.76	)		$(0.68	)		$(0.80	)		$(0.74	)		$(0.56	)
From net realized gain		(1.21	)		(0.62	)		(1.24	)		(0.92	)		(0.58	)		(0.19	)
Total distributions declared to shareholders		$(1.57	)		$(1.38	)		$(1.92	)		$(1.72	)		$(1.32	)		$(0.75	)
Net asset value, end of period (x)		$40.47			$39.01			$35.94			$33.40			$34.72			$29.82
Total return (%) (r)(s)(t)(x)		7.78	(n)		12.66	(c)		13.93			1.04			21.23			23.18
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		0.48	(a)		0.51	(c)		0.54			0.54			0.55			0.57
Expenses after expense reductions (f)		0.47	(a)		0.49	(c)		0.50			0.50			0.53			0.56
Net investment income (loss)		1.67	(a)		2.04	(c)		1.95			2.17			2.48			2.12
Portfolio turnover		7	(n)		14			12			12			13			12
Net assets at end of period (000 omitted)		$13,003,683			$10,957,734			$6,218,954			$4,846,172			$3,996			$2,632

See Notes to Financial Statements

Financial Highlights – continued


	Six months ended 2/28/18			Year ended
Class 529A	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14			8/31/13
	(unaudited)
Net asset value, beginning of period		$38.69			$35.67			$33.15			$34.48			$29.62			$24.74
Income (loss) from investment operations
Net investment income (loss) (d)		$0.26			$0.63	(c)		$0.53			$0.63			$0.69			$0.49
Net realized and unrealized gain (loss)		2.68			3.64			3.79			(0.36	)		5.38			5.05
Total from investment operations		$2.94			$4.27			$4.32			$0.27			$6.07			$5.54
Less distributions declared to shareholders
From net investment income		$(0.29	)		$(0.63	)		$(0.56	)		$(0.68	)		$(0.63	)		$(0.47	)
From net realized gain		(1.21	)		(0.62	)		(1.24	)		(0.92	)		(0.58	)		(0.19	)
Total distributions declared to shareholders		$(1.50	)		$(1.25	)		$(1.80	)		$(1.60	)		$(1.21	)		$(0.66	)
Net asset value, end of period (x)		$40.13			$38.69			$35.67			$33.15			$34.48			$29.62
Total return (%) (r)(s)(t)(x)		7.59	(n)		12.21	(c)		13.55			0.67			20.84			22.73
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		0.90	(a)		0.96	(c)		1.00			1.00			1.00			1.03
Expenses after expense reductions (f)		0.83	(a)		0.85	(c)		0.86			0.86			0.87			0.93
Net investment income (loss)		1.31	(a)		1.71	(c)		1.59			1.82			2.11			1.79
Portfolio turnover		7	(n)		14			12			12			13			12
Net assets at end of period (000 omitted)		$24,245			$22,490			$18,625			$16,543			$14,547			$10,899

See Notes to Financial Statements

Financial Highlights – continued


	Six months ended 2/28/18			Year ended
Class 529B	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14			8/31/13
	(unaudited)
Net asset value, beginning of period		$38.23			$35.27			$32.78			$34.08			$29.29			$24.48
Income (loss) from investment operations
Net investment income (loss) (d)		$0.10			$0.47	(c)		$0.29			$0.47			$0.42			$0.27
Net realized and unrealized gain (loss)		2.65			3.61			3.73			(0.34	)		5.32			4.99
Total from investment operations		$2.75			$4.08			$4.02			$0.13			$5.74			$5.26
Less distributions declared to shareholders
From net investment income		$(0.12	)		$(0.50	)		$(0.29	)		$(0.51	)		$(0.37	)		$(0.26	)
From net realized gain		(1.21	)		(0.62	)		(1.24	)		(0.92	)		(0.58	)		(0.19	)
Total distributions declared to shareholders		$(1.33	)		$(1.12	)		$(1.53	)		$(1.43	)		$(0.95	)		$(0.45	)
Net asset value, end of period (x)		$39.65			$38.23			$35.27			$32.78			$34.08			$29.29
Total return (%) (r)(s)(t)(x)		7.18	(n)		11.78	(c)		12.70			0.27			19.85			21.74
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.65	(a)		1.34	(c)		1.68			1.37			1.75			1.78
Expenses after expense reductions (f)		1.61	(a)		1.26	(c)		1.58			1.27			1.67			1.71
Net investment income (loss)		0.53	(a)		1.28	(c)		0.87			1.38			1.30			1.00
Portfolio turnover		7	(n)		14			12			12			13			12
Net assets at end of period (000 omitted)		$963			$908			$941			$888			$1,026			$1,013

See Notes to Financial Statements

Financial Highlights – continued


	Six months ended 2/28/18			Year ended
Class 529C	Six months ended 2/28/18			8/31/17			8/31/16			8/31/15			8/31/14			8/31/13
	(unaudited)
Net asset value, beginning of period		$38.07			$35.11			$32.66			$34.00			$29.23			$24.43
Income (loss) from investment operations
Net investment income (loss) (d)		$0.10			$0.34	(c)		$0.26			$0.35			$0.41			$0.27
Net realized and unrealized gain (loss)		2.64			3.59			3.73			(0.36	)		5.32			4.99
Total from investment operations		$2.74			$3.93			$3.99			$(0.01	)		$5.73			$5.26
Less distributions declared to shareholders
From net investment income		$(0.13	)		$(0.35	)		$(0.30	)		$(0.41	)		$(0.38	)		$(0.27	)
From net realized gain		(1.21	)		(0.62	)		(1.24	)		(0.92	)		(0.58	)		(0.19	)
Total distributions declared to shareholders		$(1.34	)		$(0.97	)		$(1.54	)		$(1.33	)		$(0.96	)		$(0.46	)
Net asset value, end of period (x)		$39.47			$38.07			$35.11			$32.66			$34.00			$29.23
Total return (%) (r)(s)(t)(x)		7.17	(n)		11.38	(c)		12.64			(0.14	)		19.85			21.80
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.65	(a)		1.71	(c)		1.75			1.75			1.75			1.78
Expenses after expense reductions (f)		1.60	(a)		1.63	(c)		1.65			1.66			1.67			1.72
Net investment income (loss)		0.53	(a)		0.93	(c)		0.80			1.03			1.28			1.00
Portfolio turnover		7	(n)		14			12			12			13			12
Net assets at end of period (000 omitted)		$6,177			$5,924			$5,381			$4,434			$3,981			$3,387

See Notes to Financial Statements

Financial Highlights – continued

(a)	Annualized.

(c)	Amount reflects a one-time reimbursement of expenses by the custodian (or former custodian) without which net investment income and performance would be lower and expenses would be higher.

(d)	Per share data is based on average shares outstanding.

(f)	Ratios do not reflect reductions from fees paid indirectly, if applicable.

(n)	Not annualized.

(r)	Certain expenses have been reduced without which performance would have been lower.

(s)	From time to time the fund may receive proceeds from litigation settlements, without which performance would be lower.

(t)	Total returns do not include any applicable sales charges.

(x)	The net asset values and total returns have been calculated on net assets which include adjustments made in accordance with U.S. generally accepted accounting principles required at period end for financial reporting purposes.

See Notes to Financial Statements

NOTES TO FINANCIAL STATEMENTS

(unaudited)

(1) Business and Organization

MFS Value Fund (the fund) is a diversified series of MFS Series Trust I (the trust). The trust is organized as a Massachusetts business trust and is registered under the Investment Company Act of 1940, as amended, as an open-end management investment company.

(2) Significant Accounting Policies

Notes to Financial Statements (unaudited) – continued

the fair value of investments. The following is a summary of the levels used as of February 28, 2018 in valuing the fund’s assets or liabilities:


Financial Instruments	Level 1		Level 2		Level 3		Total
Equity Securities:
United States		$45,042,626,804		$—		$—		$45,042,626,804
Switzerland		—		928,744,149		—		928,744,149
United Kingdom		545,050,419		224,029,527		—		769,079,946
Canada		255,799,766		—		—		255,799,766
France		—		222,878,843		—		222,878,843
Mutual Funds		732,081,951		—		—		732,081,951
Total		$46,575,558,940		$1,375,652,519		$—		$47,951,211,459

For further information regarding security characteristics, see the Portfolio of Investments.

Of the level 2 investments presented above, equity investments amounting to $1,151,622,992 would have been considered level 1 investments at the beginning of the period. The primary reason for changes in the classifications between levels 1 and 2 occurs when foreign equity securities are fair valued using other observable market-based inputs in place of the closing exchange price due to events occurring after the close of the exchange or market on which the investment is principally traded. The fund’s foreign equity securities may often be valued using other observable market-based inputs. The fund’s policy is to recognize transfers between the levels as of the end of the period.

Notes to Financial Statements (unaudited) – continued

event of Borrower default, State Street will, for the benefit of the fund, either purchase securities identical to those loaned or, when such purchase is commercially impracticable, pay the fund the market value of the loaned securities. In return, State Street assumes the fund’s rights to the related collateral. If the collateral value is less than the cost to purchase identical securities, State Street is responsible for the shortfall, but only to the extent that such shortfall is not due to a decline in collateral value resulting from collateral reinvestment for which the fund bears the risk of loss. A portion of the income generated upon investment of the collateral is remitted to the Borrowers, and the remainder is allocated between the fund and the lending agent. On loans collateralized by U.S. Treasury and/or federal agency obligations, a fee is received from the Borrower, and is allocated between the fund and the lending agent. Income from securities lending is separately reported in the Statement of Operations. The dividend and interest income earned on the securities loaned is accounted for in the same manner as other dividend and interest income. At February 28, 2018, there were no securities on loan or collateral outstanding.

Notes to Financial Statements (unaudited) – continued

in which the fund invests. Additionally, capital gains realized by the fund on securities issued in or by certain foreign countries may be subject to capital gains tax imposed by those countries.

Book/tax differences primarily relate to wash sale loss deferrals, treating a portion of the proceeds from redemptions as a distribution for tax purposes, and redemptions in-kind.


	Year ended 8/31/17
Ordinary income (including any short-term capital gains)		$767,688,873
Long-term capital gains		686,739,618
Total distributions		$1,454,428,491

The federal tax cost and the tax basis components of distributable earnings were as follows:


As of 2/28/18
Cost of investments	$30,467,450,017
Gross appreciation	17,990,629,656
Gross depreciation	(506,868,214	)
Net unrealized appreciation (depreciation)	$17,483,761,442

As of 8/31/17
Undistributed ordinary income	238,199,458
Undistributed long-term capital gain	826,042,751
Other temporary differences	221,135
Net unrealized appreciation (depreciation)	15,313,539,485

The aggregate cost above includes prior fiscal year end tax adjustments, if applicable.

Notes to Financial Statements (unaudited) – continued

separately for each class. Differences in per share dividend rates are generally due to differences in separate class expenses. Class B and Class 529B shares will convert to Class A and Class 529A shares approximately eight years after purchase. Effective April 23, 2018, Class C and Class 529C shares will convert to Class A and Class 529A shares, respectively, approximately ten years after purchase. The fund’s distributions declared to shareholders as reported in the Statements of Changes in Net Assets are presented by class as follows:


	From net investment income				From net realized gain
	Six months ended 2/28/18		Year ended 8/31/17		Six months ended 2/28/18		Year ended 8/31/17
Class A		$45,421,408		$131,982,827		$186,688,046		$145,815,548
Class B		420,400		1,409,681		3,950,558		2,559,725
Class C		4,605,735		14,571,557		41,974,501		26,261,814
Class I		172,916,409		375,506,835		602,257,349		303,900,025
Class R1		92,530		260,861		825,125		444,176
Class R2		3,641,323		8,856,685		18,360,568		10,120,565
Class R3		15,631,970		33,433,839		65,139,368		32,531,493
Class R4		27,918,119		62,561,506		99,811,881		55,201,840
Class R6		106,823,886		138,688,255		358,857,685		109,454,646
Class 529A		168,729		348,807		706,810		337,407
Class 529B		2,935		12,287		28,292		15,161
Class 529C		19,782		55,733		186,817		97,218
Total		$377,663,226		$767,688,873		$1,378,787,000		$686,739,618

(3) Transactions with Affiliates


Up to $7.5 billion			0.60%
In excess of $7.5 billion and up to $10 billion			0.53%
In excess of $10 billion and up to $20 billion			0.50%
In excess of $20 billion and up to $25 billion			0.45%
In excess of $25 billion and up to $30 billion			0.42%
In excess of $30 billion and up to $35 billion			0.40%
In excess of $35 billion and up to $40 billion			0.38%
In excess of $40 billion and up to $45 billion			0.36%
In excess of $45 billion			0.35%

MFS has also agreed in writing to reduce its management fee by a specified amount if certain MFS mutual fund assets exceed thresholds agreed to by MFS and the fund’s Board of Trustees. For the six months ended February 28, 2018, this management fee reduction amounted to $2,004,844, which is included in the reduction of total expenses in the Statement of Operations. The management fee incurred for the six months ended February 28, 2018 was equivalent to an annual effective rate of 0.45% of the fund’s average daily net assets.

Notes to Financial Statements (unaudited) – continued

Distributor – MFS Fund Distributors, Inc. (MFD), a wholly-owned subsidiary of MFS, as distributor, received $602,204 and $6,853 for the six months ended February 28, 2018, as its portion of the initial sales charge on sales of Class A and Class 529A shares of the fund, respectively.

The Board of Trustees has adopted a distribution plan for certain share classes pursuant to Rule 12b-1 of the Investment Company Act of 1940.

Distribution Plan Fee Table:


	Distribution Fee Rate (d)		Service Fee Rate (d)		Total Distribution Plan (d)		Annual Effective Rate (e)		Distribution and Service Fee
Class A		—		0.25%		0.25%		0.25%		$7,979,409
Class B		0.75%		0.25%		1.00%		1.00%		677,679
Class C		0.75%		0.25%		1.00%		1.00%		7,070,306
Class R1		0.75%		0.25%		1.00%		1.00%		138,321
Class R2		0.25%		0.25%		0.50%		0.50%		1,546,176
Class R3		—		0.25%		0.25%		0.25%		2,719,248
Class 529A		—		0.25%		0.25%		0.22%		29,638
Class 529B		0.75%		0.25%		1.00%		0.99%		4,775
Class 529C		0.75%		0.25%		1.00%		0.99%		30,930
Total Distribution and Service Fees										$20,196,482

(d)

(e)

The annual effective rates represent actual fees incurred under the distribution plan for the six months ended February 28, 2018 based on each class’s average daily net assets. MFD has voluntarily agreed to rebate a portion of each class’s 0.25% service fee attributable to accounts for which MFD retains the 0.25% service fee except for accounts attributable to MFS or its affiliates’ seed money. For the six months ended February 28, 2018, this rebate amounted to $50,063, $718, $2,063, $226, $641, $4,038, $35, and $250 for Class A, Class B, Class C, Class R2, Class R3, Class 529A, Class 529B, and Class 529C, respectively, and is included in the reduction of total expenses in the Statement of Operations.

Notes to Financial Statements (unaudited) – continued

the event of a shareholder redemption within six years of purchase. All contingent deferred sales charges are paid to MFD and during the six months ended February 28, 2018, were as follows:


	Amount
Class A		$34,118
Class B		68,604
Class C		39,639
Class 529B		65
Class 529C		75

The fund has entered into and may from time to time enter into contracts with program managers and other parties which administer the tuition programs through which an investment in the fund’s 529 share classes is made. For the period from September 1, 2017 through December 10, 2017, the fund had entered into an agreement with MFD pursuant to which MFD received an annual fee of up to 0.10% of the average daily net assets attributable to each 529 share class. MFD had agreed to waive a portion of this fee in an amount equal to 0.05% of the average daily net assets for each 529 share class. This waiver agreement terminated on December 10, 2017. For the period from September 1, 2017 through December 10, 2017, this waiver amounted to $4,198 and is included in the reduction of total expenses in the Statement of Operations. Effective December 11, 2017, the fund has entered into an agreement with MFD pursuant to which MFD receives an annual fee of up to 0.05% of the average daily net assets attributable to each 529 share class. The program manager fee incurred for the six months ended February 28, 2018 was equivalent to an annual effective rate of 0.05% of the average daily net assets attributable to each 529 share class. The services provided by MFD, or a third party with which MFD contracts, include recordkeeping and tax reporting and account services, as well as services designed to maintain the program’s compliance with the Internal Revenue Code and other regulatory requirements. Program manager fees and waivers for the six months ended February 28, 2018, were as follows:


	Fee		Waiver
Class 529A		$9,145		$3,218
Class 529B		370		131
Class 529C		2,396		849
Total Program Manager Fees and Waivers		$11,911		$4,198

Shareholder Servicing Agent – MFS Service Center, Inc. (MFSC), a wholly-owned subsidiary of MFS, receives a fee from the fund for its services as shareholder servicing agent calculated as a percentage of the average daily net assets of the fund as determined periodically under the supervision of the fund’s Board of Trustees. For the six months ended February 28, 2018, the fee was $823,902, which equated to 0.0035% annually of the fund’s average daily net assets. MFSC also receives payment from the fund for out-of-pocket expenses, sub-accounting and other shareholder servicing costs which may be paid to affiliated and unaffiliated service providers. Class R6 shares do not incur sub-accounting fees. For the six months ended February 28, 2018, these out-of-pocket expenses, sub-accounting and other shareholder servicing costs amounted to $17,004,770.

Notes to Financial Statements (unaudited) – continued

Prior to December 31, 2001, the fund had an unfunded defined benefit plan (“DB plan”) for independent Trustees. As of December 31, 2001, the Board took action to terminate the DB plan with respect to then-current and any future independent Trustees, such that the DB plan covers only certain of those former independent Trustees who retired on or before December 31, 2001. The DB plan resulted in a pension expense of $304 and is included in “Independent Trustees’ compensation” in the Statement of Operations for the six months ended February 28, 2018. The liability for deferred retirement benefits payable to certain independent Trustees under the DB plan amounted to $1,661 at February 28, 2018, and is included in “Payable for independent Trustees’ compensation” in the Statement of Assets and Liabilities.

Other – This fund and certain other funds managed by MFS (the funds) have entered into a service agreement (the ISO Agreement) which provides for payment of fees solely by the funds to Tarantino LLC in return for the provision of services of an Independent Senior Officer (ISO) for the funds. Frank L. Tarantino serves as the ISO and is an officer of the funds and the sole member of Tarantino LLC. The funds can terminate the ISO Agreement with Tarantino LLC at any time under the terms of the ISO Agreement. For the six months ended February 28, 2018, the fee paid by the fund under this agreement was $38,296 and is included in “Miscellaneous” expense in the Statement of Operations. MFS has agreed to bear all expenses associated with office space, other administrative support, and supplies provided to the ISO.

On March 16, 2017, MFS purchased 48,783 shares of Class I for an aggregate amount of $1,882,554.

The fund is permitted to engage in purchase and sale transactions with funds and accounts for which MFS serves as investment adviser or sub-adviser (“cross-trades”) pursuant to a policy adopted by the Board of Trustees. This policy has been designed to ensure that cross-trades conducted by the fund comply with Rule 17a-7 under the Investment Company Act of 1940. During the six months ended February 28, 2018, the fund engaged in purchase and sale transactions pursuant to this policy, which

Notes to Financial Statements (unaudited) – continued

amounted to $83,385,746 and $17,204,191, respectively. The sales transactions resulted in net realized gains (losses) of $(771,606).

(4) Portfolio Securities

For the six months ended February 28, 2018, purchases and sales of investments, other than short-term obligations, aggregated $3,852,232,544 and $3,256,792,595, respectively.

(5) Shares of Beneficial Interest

The fund’s Declaration of Trust permits the Trustees to issue an unlimited number of full and fractional shares of beneficial interest. Transactions in fund shares were as follows:


	Six months ended 2/28/18				Year ended 8/31/17
	Shares		Amount		Shares		Amount
Shares sold
Class A		14,380,601		$586,121,954		43,230,719		$1,600,357,205
Class B		101,700		4,116,245		409,602		15,035,351
Class C		2,016,440		81,259,701		5,986,930		219,687,272
Class I		68,384,740		2,803,509,429		243,305,782		9,165,915,403
Class R1		89,660		3,585,597		262,817		9,532,638
Class R2		1,229,857		49,601,382		4,092,565		148,873,968
Class R3		10,501,065		428,692,946		14,808,851		547,458,754
Class R4		14,217,299		585,504,669		17,657,031		656,925,761
Class R6		54,100,899		2,215,332,027		147,390,698		5,624,934,683
Class 529A		46,746		1,902,641		108,068		3,966,237
Class 529B		1,710		68,139		4,785		171,069
Class 529C		9,767		388,609		29,769		1,075,087
		165,080,484		$6,760,083,339		477,287,617		$17,993,933,428

Notes to Financial Statements (unaudited) – continued


	Six months ended 2/28/18						Year ended 8/31/17
	Shares			Amount			Shares			Amount
Shares issued to shareholders in reinvestment of distributions
Class A		4,945,202			$200,903,277			6,766,520			$248,454,218
Class B		100,677			4,075,707			99,277			3,632,741
Class C		940,824			37,824,861			799,377			29,063,578
Class I		14,687,519			599,647,295			13,652,416			506,718,218
Class R1		22,991			917,655			19,510			705,037
Class R2		511,369			20,571,333			487,452			17,778,534
Class R3		1,995,896			80,770,732			1,796,755			65,965,080
Class R4		3,028,515			122,957,095			3,045,418			112,104,718
Class R6		10,732,018			435,660,239			6,150,032			226,909,284
Class 529A		21,725			875,504			18,752			686,051
Class 529B		783			31,227			761			27,448
Class 529C		5,201			206,599			4,251			152,951
		36,992,720			$1,504,441,524			32,840,521			$1,212,197,858

Shares reacquired
Class A		(26,227,023	)		$(1,066,418,008	)		(138,738,962	)		$(5,168,833,039	)
Class B		(557,665	)		(22,691,224	)		(1,297,053	)		(47,974,161	)
Class C		(4,060,021	)		(163,672,531	)		(14,041,805	)		(519,939,313	)
Class I		(67,810,435	)		(2,782,004,968	)		(230,780,835	)		(8,789,683,191	)
Class R1		(112,579	)		(4,522,402	)		(353,521	)		(12,867,968	)
Class R2		(2,787,361	)		(112,757,485	)		(4,624,581	)		(170,766,207	)
Class R3		(8,003,506	)		(325,764,092	)		(17,523,982	)		(647,496,527	)
Class R4		(13,796,829	)		(566,023,173	)		(32,186,529	)		(1,198,570,080	)
Class R6		(24,388,817	)		(997,766,586	)		(45,654,925	)		(1,690,587,513	)
Class 529A		(45,580	)		(1,849,357	)		(67,724	)		(2,512,154	)
Class 529B		(1,966	)		(78,877	)		(8,463	)		(303,930	)
Class 529C		(14,070	)		(564,071	)		(31,658	)		(1,160,458	)
		(147,805,852	)		$(6,044,112,774	)		(485,310,038	)		$(18,250,694,541	)

Net change
Class A		(6,901,220	)		$(279,392,777	)		(88,741,723	)		$(3,320,021,616	)
Class B		(355,288	)		(14,499,272	)		(788,174	)		(29,306,069	)
Class C		(1,102,757	)		(44,587,969	)		(7,255,498	)		(271,188,463	)
Class I		15,261,824			621,151,756			26,177,363			882,950,430
Class R1		72			(19,150	)		(71,194	)		(2,630,293	)
Class R2		(1,046,135	)		(42,584,770	)		(44,564	)		(4,113,705	)
Class R3		4,493,455			183,699,586			(918,376	)		(34,072,693	)
Class R4		3,448,985			142,438,591			(11,484,080	)		(429,539,601	)
Class R6		40,444,100			1,653,225,680			107,885,805			4,161,256,454
Class 529A		22,891			928,788			59,096			2,140,134
Class 529B		527			20,489			(2,917	)		(105,413	)
Class 529C		898			31,137			2,362			67,580
		54,267,352			$2,220,412,089			24,818,100			$955,436,745

Notes to Financial Statements (unaudited) – continued

Class T shares were not publicly available for sale during the period. Please see the fund’s prospectus for details.

The fund is one of several mutual funds in which certain MFS funds may invest. The MFS funds do not invest in the underlying funds for the purpose of exercising management or control. At the end of the period, the MFS Growth Allocation Fund was the owner of record of approximately 1% of the value of outstanding voting shares of the fund. In addition, the MFS Aggressive Growth Allocation Fund, the MFS Conservative Allocation Fund, the MFS Lifetime Income Fund, the MFS Lifetime 2020 Fund, the MFS Lifetime 2025 Fund, the MFS Lifetime 2030 Fund, the MFS Lifetime 2035 Fund, the MFS Lifetime 2040 Fund, the MFS Lifetime 2045 Fund, the MFS Lifetime 2050 Fund, the MFS Lifetime 2055 Fund, the MFS Lifetime 2060 Fund, the MFS Managed Wealth Fund, and the MFS Moderate Allocation Fund were each the owners of record of less than 1% of the value of outstanding voting shares of the fund.

(6) Line of Credit

The fund and certain other funds managed by MFS participate in a $1.25 billion unsecured committed line of credit, subject to a $1 billion sublimit, provided by a syndication of banks under a credit agreement. Borrowings may be made for temporary financing needs. Interest is charged to each fund, based on its borrowings, generally at a rate equal to the higher of the Overnight Federal Reserve funds rate or daily one month LIBOR plus an agreed upon spread. A commitment fee, based on the average daily, unused portion of the committed line of credit, is allocated among the participating funds at the end of each calendar quarter. In addition, the fund and other funds managed by MFS have established unsecured uncommitted borrowing arrangements with certain banks for temporary financing needs. Interest is charged to each fund, based on its borrowings, at a rate equal to the Overnight Federal Reserve funds rate plus an agreed upon spread. For the six months ended February 28, 2018, the fund’s commitment fee and interest expense were $146,042 and $0, respectively, and are included in “Miscellaneous” expense in the Statement of Operations.

(7) Investments in Affiliated Issuers


Affiliated Issuers			Beginning Shares/Par Amount			Acquisitions Shares/Par Amount		Dispositions Shares/Par Amount			Ending Shares/Par Amount
MFS Institutional Money Market Portfolio				908,270,888			2,936,396,006		(3,112,511,727	)		732,155,167

Affiliated Issuers	Realized Gain (Loss)		Change in Unrealized Appreciation (Depreciation)			Capital Gain Distributions		Dividend Income			Ending Value
MFS Institutional Money Market Portfolio		$34,492		$(9,973	)		$—		$3,846,853			$732,081,951

PROXY VOTING POLICIES AND INFORMATION

QUARTERLY PORTFOLIO DISCLOSURE

Public Reference Room

Securities and Exchange Commission

100 F Street, NE, Room 1580

Washington, D.C. 20549

FURTHER INFORMATION

INFORMATION ABOUT FUND CONTRACTS AND LEGAL CLAIMS

PROVISION OF FINANCIAL REPORTS AND SUMMARY PROSPECTUSES

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CONTACT

WEB SITE

mfs.com

MFS TALK

1-800-637-8255

24 hours a day

ACCOUNT SERVICE AND LITERATURE

Shareholders

1-800-225-2606

Financial advisors

1-800-343-2829

Retirement plan services

1-800-637-1255

MAILING ADDRESS

MFS Service Center, Inc.

P.O. Box 55824

Boston, MA 02205-5824

OVERNIGHT MAIL

MFS Service Center, Inc.

c/o DST Asset Manager Solutions, Inc.

30 Dan Road

Canton, MA 02021-2809

ITEM 2.

CODE OF ETHICS.

During the period covered by this report, the Registrant has not amended any provision in its Code of Ethics (the “Code”) that relates to an element of the Code’s definitions enumerated in paragraph (b) of Item 2 of this Form N-CSR. During the period covered by this report, the Registrant did not grant a waiver, including an implicit waiver, from any provision of the Code.

ITEM 3.

AUDIT COMMITTEE FINANCIAL EXPERT.

Not applicable for semi-annual reports.

ITEM 4.

PRINCIPAL ACCOUNTANT FEES AND SERVICES.

Not applicable for semi-annual reports.

ITEM 5.

AUDIT COMMITTEE OF LISTED REGISTRANTS.

Not applicable to the Registrant.

ITEM 6.

INVESTMENTS

A schedule of investments for each series of the Registrant is included as part of the report to shareholders of such series under Item 1 of this Form N-CSR.

ITEM 7.

DISCLOSURE OF PROXY VOTING POLICIES AND PROCEDURES FOR CLOSED-END MANAGEMENT INVESTMENT COMPANIES.

Not applicable to the Registrant.

ITEM 8.

PORTFOLIO MANAGERS OF CLOSED-END MANAGEMENT INVESTMENT COMPANIES.

Not applicable to the Registrant.

ITEM 9.

PURCHASES OF EQUITY SECURITIES BY CLOSED-END MANAGEMENT INVESTMENT COMPANY AND AFFILIATED PURCHASERS.

Not applicable to the Registrant.

ITEM 10.

SUBMISSION OF MATTERS TO A VOTE OF SECURITY HOLDERS.

There were no material changes to the procedures by which shareholders may send recommendations to the Board for nominees to the Registrant’s Board since the Registrant last provided disclosure as to such procedures in response to the requirements of Item 407 (c)(2)(iv) of Regulation S-K or this Item.

ITEM 11.

CONTROLS AND PROCEDURES.

(a)

Based upon their evaluation of the effectiveness of the registrant’s disclosure controls and procedures (as defined in Rule 30a-3(c) under the Investment Company Act of 1940 (the “Act”)) as conducted within 90 days of the filing date of this report on Form N-CSR, the registrant’s principal financial officer and principal executive officer have concluded that those disclosure controls and procedures provide reasonable assurance that the material information required to be disclosed by the registrant on this report is recorded, processed, summarized and reported within the time periods specified in the Securities and Exchange Commission’s rules and forms.

(b)

There were no changes in the registrant’s internal controls over financial reporting (as defined in Rule 30a-3(d) under the Act) that occurred during the second fiscal quarter of the period covered by the report that have materially affected, or are reasonably likely to materially affect, the registrant’s internal control over financial reporting.

ITEM 12.

DISCLOSURE OF SECURITIES LENDING ACTIVITIES FOR CLOSED-END MANAGEMENT INVESTMENT COMPANIES.

Not applicable to the Registrant.

ITEM 13.

EXHIBITS.

(a)	File the exhibits listed below as part of this form. Letter or number the exhibits in the sequence indicated.

(1)

Any code of ethics, or amendment thereto, that is the subject of the disclosure required by Item 2, to the extent that the registrant intends to satisfy the Item 2 requirements through filing of an exhibit.

(2)

A separate certification for each principal executive officer and principal financial officer of the registrant as required by Rule 30a-2(a) under the Act (17 CFR 270.30a-2): Attached hereto.

(b)

If the report is filed under Section 13(a) or 15(d) of the Exchange Act, provide the certifications required by Rule 30a-2(b) under the Act (17 CFR 270.30a-2(b)), Rule 13a-14(b) or Rule 15d-14(b) under the Exchange Act (17 CFR 240.13a-14(b) or 240.15d-14(b)) and Section 1350 of Chapter 63 of Title 18 of the United States Code (18 U.S.C. 1350) as an exhibit. A certification furnished pursuant to this paragraph will not be deemed “filed” for the purposes of Section 18 of the Exchange Act (15 U.S.C. 78r), or otherwise subject to the liability of that section. Such certification will not be deemed to be incorporated by reference into any filing under the Securities Act of 1933 or the Exchange Act, except to the extent that the registrant specifically incorporates it by reference: Attached hereto.

Notice

A copy of the Amended and Restated Declaration of Trust, as amended, of the Registrant is on file with the Secretary of State of The Commonwealth of Massachusetts and notice is hereby given that this instrument is executed on behalf of the Registrant by an officer of the Registrant as an officer and not individually and the obligations of or arising out of this instrument are not binding upon any of the Trustees or shareholders individually, but are binding only upon the assets and property of the respective constituent series of the Registrant.

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934 and the Investment Company Act of 1940, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

(Registrant) MFS SERIES TRUST I


By (Signature and Title)*		DAVID L. DILORENZO
		David L. DiLorenzo, President

Date: April 13, 2018

Pursuant to the requirements of the Securities Exchange Act of 1934 and the Investment Company Act of 1940, this report has been signed below by the following persons on behalf of the registrant and in the capacities and on the dates indicated.


By (Signature and Title)*		DAVID L. DILORENZO
		David L. DiLorenzo, President (Principal Executive Officer)

Date: April 13, 2018


By (Signature and Title)*		JAMES O. YOST
		James O. Yost, Treasurer (Principal Financial Officer and Accounting Officer)

Date: April 13, 2018

*	Print name and title of each signing officer under his or her signature.

MFS Series Trust I - MFS Value Fund (MEIAX) N-CSRSCertified semi-annual shareholder report (management investment company)