UDR (UDR) 10-Q 28 Apr 21 2021 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2021	Apr. 26, 2021
Document and Entity Information
Document Type	10-Q
Document Quarterly Report	true
Document Transition Report	false
Document Period End Date	Mar. 31, 2021
Entity File Number	1-10524
Entity Registrant Name	UDR, Inc.
Entity Incorporation, State or Country Code	MD
Entity Tax Identification Number	54-0857512
Entity Address, Address Line One	1745 Shea Center Drive, Suite 200
Entity Address, City or Town	Highlands Ranch
Entity Address, State or Province	CO
Entity Address, Postal Zip Code	80129
City Area Code	720
Local Phone Number	283-6120
Title of 12(b) Security	Common Stock, par value $0.01
Trading Symbol	UDR
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		296,834,603
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q1
Entity Central Index Key	0000074208
Amendment Flag	false

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Real estate owned:
Real estate held for investment	$ 12,852,700	$ 12,706,940
Less: accumulated depreciation	(4,729,702)	(4,590,577)
Real estate held for investment, net	8,122,998	8,116,363
Real estate under development (net of accumulated depreciation of $319 and $1,010, respectively)	242,881	246,867
Real estate held for disposition (net of accumulated depreciation of $0 and $13,779, respectively)		102,876
Total real estate owned, net of accumulated depreciation	8,365,879	8,466,106
Cash and cash equivalents	1,172	1,409
Restricted cash	33,428	22,762
Notes receivable, net	155,206	157,992
Investment in and advances to unconsolidated joint ventures, net	620,111	600,233
Operating lease right-of-use assets	200,064	200,913
Other assets	190,696	188,118
Total assets	9,566,556	9,637,533
Liabilities:
Secured debt, net	919,177	862,147
Unsecured debt, net	4,121,998	4,114,401
Operating lease liabilities	194,829	195,592
Real estate taxes payable	32,437	29,946
Accrued interest payable	23,149	44,760
Security deposits and prepaid rent	47,968	49,008
Distributions payable	116,693	115,795
Accounts payable, accrued expenses, and other liabilities	104,218	110,999
Total liabilities	5,560,469	5,522,648
Commitments and contingencies (Note 13)
Redeemable noncontrolling interests in the Operating Partnership and DownREIT Partnership	989,686	856,294
Equity:
Common stock, $0.01 par value; 350,000,000 shares authorized: 296,822,363 and 296,611,579 shares issued and outstanding at March 31, 2021 and December 31, 2020, respectively	2,968	2,966
Additional paid-in capital	5,885,682	5,881,383
Distributions in excess of net income	(2,923,073)	(2,685,770)
Accumulated other comprehensive income/(loss), net	(8,614)	(9,144)
Total stockholders' equity	3,001,728	3,234,200
Noncontrolling interests	14,673	24,391
Total equity	3,016,401	3,258,591
Total liabilities and equity	9,566,556	9,637,533
8.00% Series E Cumulative Convertible Preferred Stock
Equity:
Preferred stock, no par value; 50,000,000 shares authorized:	44,764	44,764
Series F
Equity:
Preferred stock, no par value; 50,000,000 shares authorized:	$ 1	$ 1

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Real estate owned:
Real estate under development accumulated depreciation	$ 319	$ 1,010
Real estate held for disposition accumulated depreciation	$ 0	$ 13,779
Equity:
Preferred stock, no par value	$ 0	$ 0
Preferred stock, shares authorized	50,000,000	50,000,000
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	350,000,000	350,000,000
Common stock, shares issued	296,822,363	296,611,579
Common stock, shares outstanding	296,822,363	296,611,579
8.00% Series E Cumulative Convertible Preferred Stock
Equity:
Preferred stock, dividend rate percentage	8.00%	8.00%
Preferred stock, shares issued	2,695,363	2,695,363
Preferred stock, shares outstanding	2,695,363	2,695,363
Series F
Equity:
Preferred stock, shares issued	14,374,488	14,440,519
Preferred stock, shares outstanding	14,374,488	14,440,519

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
REVENUES:
Rental income	$ 299,826	$ 320,093
Joint venture management and other fees	$ 1,615	$ 1,388
Type of revenue	udr:ManagementAndOtherFeesMember	udr:ManagementAndOtherFeesMember
Total revenues	$ 301,441	$ 321,481
OPERATING EXPENSES:
Property operating and maintenance	51,381	49,483
Real estate taxes and insurance	47,387	45,145
Property management	8,995	9,203
Other operating expenses	4,435	4,966
Real estate depreciation and amortization	144,088	155,476
General and administrative	12,736	14,978
Casualty-related charges/(recoveries), net	5,577	1,251
Other depreciation and amortization	2,601	2,025
Total operating expenses	277,200	282,527
Gain/(loss) on sale of real estate owned	50,829
Operating income	75,070	38,954
Income/(loss) from unconsolidated entities	4,922	3,367
Interest expense	(78,156)	(39,317)
Interest income and other income/(expense), net	2,057	2,700
Income/(loss) before income taxes	3,893	5,704
Tax (provision)/benefit, net	(619)	(164)
Net income/(loss)	3,274	5,540
Net (income)/loss attributable to redeemable noncontrolling interests in the Operating Partnership and DownREIT Partnership	(154)	(313)
Net (income)/loss attributable to noncontrolling interests	(16)	(6)
Net income/(loss) attributable to UDR, Inc.	3,104	5,221
Distributions to preferred stockholders - Series E (Convertible)	(1,056)	(1,066)
Net income/(loss) attributable to common stockholders	$ 2,048	$ 4,155
Income/(loss) per weighted average common share - basic	$ 0.01	$ 0.01
Income/(loss) per weighted average common share - diluted	$ 0.01	$ 0.01
Weighted average number of common shares outstanding - basic	296,537	294,457
Weighted average number of common shares outstanding - diluted	297,026	295,160

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME/(LOSS) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME/(LOSS)
Net income/(loss)	$ 3,274	$ 5,540
Other comprehensive income/(loss), including portion attributable to noncontrolling interests:
Unrealized holding gain/(loss)	127	(2,917)
(Gain)/loss reclassified into earnings from other comprehensive income/(loss)	446	357
Other comprehensive income/(loss), including portion attributable to noncontrolling interests	573	(2,560)
Comprehensive income/(loss)	3,847	2,980
Comprehensive (income)/loss attributable to noncontrolling interests	(213)	(181)
Comprehensive income/(loss) attributable to UDR, Inc.	$ 3,634	$ 2,799

CONSOLIDATED STATEMENTS OF CHAN

CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY - USD ($) $ in Thousands	Preferred Stock	Common Stock	Paid-in Capital	Distributions in Excess of Net IncomeAdjustment	Distributions in Excess of Net Income	Accumulated Other Comprehensive Income/(Loss), net	Noncontrolling Interests	Adjustment	Total
Consolidated Statements of Changes in Equity
Cumulative effect upon adoption of ASC 326	$ 46,201	$ 2,946	$ 5,781,975	$ (2,182)	$ (2,462,132)	$ (10,448)	$ 30,772	$ (2,182)	$ 3,389,314
Beginning Balance at Dec. 31, 2019	46,201	2,946	5,781,975	(2,182)	(2,462,132)	(10,448)	30,772	(2,182)	3,389,314
Consolidated Statements of Changes in Equity
Net income/(loss) attributable to UDR, Inc.					5,221				5,221
Net income/(loss) attributable to noncontrolling interests							(10)		(10)
Long Term Incentive Plan Unit grants/(vestings), net							(16,487)		(16,487)
Other comprehensive income/(loss)						(2,422)			(2,422)
Issuance/(forfeiture) of common and restricted shares, net		1	(1,332)						(1,331)
Cumulative effect upon adoption of ASC 326	46,201	2,949	5,788,471	$ (2,182)	(2,360,636)	(12,870)	14,275	$ (2,182)	3,478,390
Adjustment for conversion of noncontrolling interest of unitholders in the Operating Partnership and DownREIT Partnership		2	7,828						7,830
Common stock distributions declared					(106,190)				(106,190)
Preferred stock distributions declared-Series E					(1,066)				(1,066)
Adjustment to reflect redemption value of redeemable noncontrolling interests					205,713				205,713
Ending Balance at Mar. 31, 2020	46,201	2,949	5,788,471		(2,360,636)	(12,870)	14,275		3,478,390
Consolidated Statements of Changes in Equity
Cumulative effect upon adoption of ASC 326	46,201	2,949	5,788,471		(2,360,636)	(12,870)	14,275		3,478,390
Cumulative effect upon adoption of ASC 326	44,765	2,966	5,881,383		(2,685,770)	(9,144)	24,391		3,258,591
Beginning Balance at Dec. 31, 2020	44,765	2,966	5,881,383		(2,685,770)	(9,144)	24,391		3,258,591
Consolidated Statements of Changes in Equity
Net income/(loss) attributable to UDR, Inc.					3,104				3,104
Net income/(loss) attributable to noncontrolling interests							8		8
Redemption of noncontrolling interests in consolidated real estate							(125)		(125)
Long Term Incentive Plan Unit grants/(vestings), net							(9,601)		(9,601)
Other comprehensive income/(loss)						530			530
Issuance/(forfeiture) of common and restricted shares, net		1	(197)						(196)
Cumulative effect upon adoption of ASC 326	44,765	2,968	5,885,682		(2,923,073)	(8,614)	14,673		3,258,591
Adjustment for conversion of noncontrolling interest of unitholders in the Operating Partnership and DownREIT Partnership		1	4,496						4,497
Common stock distributions declared					(107,651)				(107,651)
Preferred stock distributions declared-Series E					(1,056)				(1,056)
Adjustment to reflect redemption value of redeemable noncontrolling interests					(131,700)				(131,700)
Ending Balance at Mar. 31, 2021	44,765	2,968	5,885,682		(2,923,073)	(8,614)	14,673		3,016,401
Consolidated Statements of Changes in Equity
Cumulative effect upon adoption of ASC 326	$ 44,765	$ 2,968	$ 5,885,682		$ (2,923,073)	$ (8,614)	$ 14,673		$ 3,016,401

CONSOLIDATED STATEMENTS OF CH_2

CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY (Parenthetical) - $ / shares	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Common stock distributions declared per share	$ 0.3625	$ 0.36
8.00% Series E Cumulative Convertible Preferred Stock
Preferred stock distributions declared	$ 0.3925	$ 0.3898

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Operating Activities
Net income/(loss)	$ 3,274	$ 5,540
Adjustments to reconcile net income/(loss) to net cash provided by/(used in) operating activities:
Depreciation and amortization	146,689	157,501
(Gain)/loss on sale of real estate owned	(50,829)
(Income)/loss from unconsolidated entities	(4,922)	(3,367)
Return on investment in unconsolidated joint ventures	1,094	1,741
Amortization of share-based compensation	4,912	6,808
Loss on extinguishment of debt, net	41,950
Other	2,766	(1,215)
Changes in operating assets and liabilities:
(Increase)/decrease in operating assets	18	114
Increase/(decrease) in operating liabilities	(21,347)	(31,666)
Net cash provided by/(used in) operating activities	123,605	135,456
Investing Activities
Acquisition of real estate assets	(23,693)	(141,727)
Proceeds from sales of real estate investments, net	154,857
Development of real estate assets	(32,683)	(23,087)
Capital expenditures and other major improvements - real estate assets	(28,424)	(32,983)
Capital expenditures - non-real estate assets	(3,041)	(2,479)
Investment in unconsolidated joint ventures	(48,604)	(16,139)
Distributions received from unconsolidated joint ventures	32,648	3,271
Purchase deposits on pending acquisitions	(12,821)
Repayment/(issuance) of notes receivable, net	2,800	(900)
Net cash provided by/(used in) investing activities	41,039	(214,044)
Financing Activities
Payments on secured debt	(270)	(2,781)
Payments on unsecured debt	(300,000)
Net proceeds from the issuance of unsecured debt	298,776	211,320
Net proceeds/(repayment) of commercial paper	20,000	(85,000)
Net proceeds/(repayment) of revolving bank debt	(10,210)	58,214
Distributions paid to redeemable noncontrolling interests	(8,517)	(7,618)
Distributions paid to preferred stockholders	(1,045)	(1,015)
Distributions paid to common stockholders	(106,833)	(100,930)
Payment of prepayment and extinguishment costs	(40,769)
Other	(5,347)	(3,964)
Net cash provided by/(used in) financing activities	(154,215)	68,226
Net increase/(decrease) in cash, cash equivalents, and restricted cash	10,429	(10,362)
Cash, cash equivalents, and restricted cash, beginning of year	24,171	33,291
Cash, cash equivalents, and restricted cash, end of period	34,600	22,929
Supplemental Information:
Interest paid during the period, net of amounts capitalized	56,281	54,109
Operating cash flows from operating leases	3,126	3,126
Cash paid/(refunds received) for income taxes	(36)	323
Non-cash transactions:
Secured debt assumed upon acquisition of real estate assets	58,464
Transfer of investment in and advances to unconsolidated joint ventures to real estate owned		14,700
Acquisition of intellectual property in exchange for cancellation of secured note receivable		2,250
Recognition of allowance for credit losses		2,182
Vesting of LTIP Units	14,578	23,018
Development costs and capital expenditures incurred, but not yet paid	31,628	25,568
Conversion of Operating Partnership and DownREIT Partnership noncontrolling interests to common stock (116,997 shares in 2021 and 167,631 shares in 2020)	4,497	7,830
Dividends declared, but not yet paid	$ 116,693	$ 115,259

CONSOLIDATED STATEMENTS OF CA_2

CONSOLIDATED STATEMENTS OF CASH FLOWS - SUPPLEMENTAL - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020	Dec. 31, 2019
The following reconciles cash, cash equivalents, and restricted cash to amounts as shown above:
Cash and cash equivalents	$ 1,172	$ 1,409	$ 980	$ 8,106
Restricted cash	33,428	22,762	21,949	25,185
Total cash, cash equivalents, and restricted cash as shown above	$ 34,600	$ 24,171	$ 22,929	$ 33,291

CONSOLIDATED STATEMENTS OF CA_3

CONSOLIDATED STATEMENTS OF CASH FLOWS (Parenthetical) - shares	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Non-cash transactions:
Conversion of OP Units into common shares	116,997	167,631

BASIS OF PRESENTATION

BASIS OF PRESENTATION	3 Months Ended
	Mar. 31, 2021
BASIS OF PRESENTATION
BASIS OF PRESENTATION	1. BASIS OF PRESENTATION Basis of Presentation UDR, Inc., collectively with our consolidated subsidiaries (“UDR,” the “Company,” “we,” “our,” or “us”), is a self-administered real estate investment trust, or REIT, that owns, operates, acquires, renovates, develops, redevelops, and manages apartment communities. The accompanying consolidated financial statements include the accounts of UDR and its subsidiaries, including United Dominion Realty, L.P. (the “Operating Partnership” or the “OP”) and UDR Lighthouse DownREIT L.P. (the “DownREIT Partnership”). As of March 31, 2021, there were 185.2 million units in the Operating Partnership (“OP Units”) outstanding, of which 176.2 million OP Units (including 0.1 million of general partnership units), or 95.1%, were owned by UDR and 9.0 million OP Units, or 4.9%, were owned by outside limited partners. As of March 31, 2021, there were 32.4 million units in the DownREIT Partnership (“DownREIT Units”) outstanding, of which 18.8 million, or 58.0%, were owned by UDR and its subsidiaries and 13.6 million, or 42.0%, were owned by outside limited partners. The consolidated financial statements of UDR include the noncontrolling interests of the unitholders in the Operating Partnership and DownREIT Partnership. The accompanying interim unaudited consolidated financial statements have been prepared according to the rules and regulations of the Securities and Exchange Commission (the “SEC”). Certain information and note disclosures normally included in financial statements prepared in accordance with accounting principles generally accepted in the United States have been condensed or omitted according to such rules and regulations, although management believes that the disclosures are adequate to make the information presented not misleading. In the opinion of management, all adjustments and eliminations necessary for the fair presentation of our financial position as of March 31, 2021, and results of operations for the three months ended March 31, 2021 and 2020, have been included. Such adjustments are normal and recurring in nature. The interim results presented are not necessarily indicative of results that can be expected for a full year, particularly in light of the novel coronavirus disease (“COVID-19”) pandemic and measures intended to mitigate its spread. The accompanying interim unaudited consolidated financial statements should be read in conjunction with the audited consolidated financial statements and related notes for the year ended December 31, 2020 appearing in UDR’s Annual Report on Form 10-K, filed with the SEC on February 18, 2021. The accompanying interim unaudited consolidated financial statements are presented in accordance with U.S. generally accepted accounting principles (“GAAP”). GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent liabilities at the dates of the interim unaudited consolidated financial statements and the amounts of revenues and expenses during the reporting periods. Actual amounts realized or paid could differ from those estimates. All significant intercompany accounts and transactions have been eliminated in consolidation. The Company evaluated subsequent events through the date its financial statements were issued. No significant recognized or non-recognized subsequent events were noted other than those noted in Note 2, Significant Accounting Policies Real Estate Owned, , Joint Ventures and Partnerships Secured and Unsecured Debt, Net , Commitments and Contingencies

SIGNIFICANT ACCOUNTING POLICIES

SIGNIFICANT ACCOUNTING POLICIES	3 Months Ended
	Mar. 31, 2021
SIGNIFICANT ACCOUNTING POLICIES
SIGNIFICANT ACCOUNTING POLICIES	2. SIGNIFICANT ACCOUNTING POLICIES Recent Accounting Pronouncements In March 2020, the SEC adopted rules that amended the financial disclosure requirements for subsidiary issuers and guarantors of registered debt securities in Rule 3-10 of Regulation S-X. Subsequently, in November 2020, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2020-09, Debt (Topic 470): Amendments to SEC Paragraphs Pursuant to SEC Release No. 33-10762, which revises SEC paragraphs of the codification to reflect, as appropriate, the amended disclosure requirements mentioned above. Under the amended rules, parent companies can provide alternative disclosures in lieu of separate audited financial statements of subsidiary issuers and guarantors that meet certain criteria. We evaluated the criteria and determined that we are eligible for the exceptions, which allow us to provide alternative disclosures for the Operating Partnership, which guarantees certain outstanding debt securities issued by the Company. Both rules became effective for the Company on January 4, 2021, and we adopted these amendments for the three months ended March 31, 2021. As a result of the amendments, the Operating Partnership, as subsidiary guarantor, is no longer subject to the filing requirements under Section 15(d) of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), and will no longer file separate periodic and current reports in reliance on Rule 12h-5 under the Exchange Act. The alternative disclosures related to the Operating Partnership are presented in Item 2 "Management's Discussion and Analysis of Financial Condition and Results of Operations” in this report. ​ I n August 2020, the FASB issued ASU 2020-06, Debt—Debt With Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging—Contracts in E ntity’s Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity ​ In March 2020, the FASB issued ASU 2020-04, Reference Rate Reform (Topic 848) ​ Principles of Consolidation The Company accounts for subsidiary partnerships, joint ventures and other similar entities in which it holds an ownership interest in accordance with the consolidation guidance. The Company first evaluates whether each entity is a variable interest entity (“VIE”). Under the VIE model, the Company consolidates an entity when it has control to direct the activities of the VIE and the obligation to absorb losses or the right to receive benefits that could potentially be significant to the VIE. Under the voting model, the Company consolidates an entity when it controls the entity through ownership of a majority voting interest. Real Estate Sales Gain Recognition ​ For sale transactions resulting in a transfer of a controlling financial interest of a property, the Company generally derecognizes the related assets and liabilities from its Consolidated Balance Sheets and records the gain or loss in the period in which the transfer of control occurs. If control of the property has not transferred to the counterparty, the criteria for derecognition are not met and the Company will continue to recognize the related assets and liabilities on its Consolidated Balance Sheets. ​ Sale transactions to entities in which the Company sells a controlling financial interest in a property but retains a noncontrolling interest are accounted for as partial sales. Partial sales resulting in a change in control are accounted for at fair value and a full gain or loss is recognized. Therefore, the Company will record a gain or loss on the partial interest sold, and the initial measurement of our retained interest will be accounted for at fair value. ​ Sales of real estate to joint ventures or other noncontrolled investees are also accounted for at fair value and the Company will record a full gain or loss in the period the property is contributed. ​ To the extent that the Company acquires a controlling financial interest in a property that it previously accounted for as an equity method investment, the Company will not remeasure its previously held interest if the acquisition is treated as an asset acquisition. The Company will include the carrying amount of its previously held equity method interest along with the consideration paid and transaction costs incurred in determining the amounts to allocate to the related assets and liabilities acquired on its Consolidated Balance Sheets. When treated as an asset acquisition, the Company will not recognize a gain or loss on consolidation of a property. ​ Allowance for Credit Losses The Company accounts for allowance for credit losses under the current expected credit loss (“CECL”) impairment model for its financial assets, including trade and other receivables, held-to-maturity debt securities, loans and other financial instruments, and presents the net amount of the financial instrument expected to be collected. The CECL impairment model excludes operating lease receivables. The CECL impairment model requires an estimate of expected credit losses, measured over the contractual life of an instrument, that considers forecasts of future economic conditions in addition to information about past events and current conditions. Based on this model, we analyze the following criteria, as applicable in developing allowances for credit losses: historical loss information, the borrower’s ability to make scheduled payments, the remaining time to maturity, the value of underlying collateral, projected future performance of the borrower and macroeconomic trends. ​ The Company measures credit losses of financial assets on a collective (pool) basis when similar risk characteristics exist. If the Company determines that a financial asset does not share risk characteristics with its other financial assets, the Company evaluates the financial asset for expected credit losses on an individual basis. Allowance for credit losses are recorded as a direct reduction from an asset’s amortized cost basis. Credit losses and recoveries are recorded in Interest income and other income/(expense), net ​ The Company has made the optional election provided by the standard not to measure allowance for credit losses for accrued interest receivables as the Company writes off any uncollectible accrued interest receivables in a timely manner. The Company periodically evaluates the collectability of its accrued interest receivables. A write-off is recorded when the Company concludes that all or a portion of its accrued interest receivable balance is no longer collectible. ​ Notes Receivable Notes receivable relate to financing arrangements which are typically secured by real estate, real estate related projects or other assets. Certain of the loans we extend may include characteristics such as options to purchase the project within a specific time window following expected project completion. These characteristics can cause the loans to fall under the definition of a VIE, and thus trigger consolidation consideration. We consider the facts and circumstances pertinent to each loan, including the relative amount of financing we are contributing to the overall project cost, decision making rights or control we hold, and our rights to expected residual gains or our obligations to absorb expected residual losses from the project. If we are deemed to be the primary beneficiary of a VIE due to holding a controlling financial interest, the majority of decision making control, or by other means, consolidation of the VIE would be required. The Company has concluded that it is not the primary beneficiary of the borrowing entities. Additionally, we analyze each loan arrangement that involves real estate development to consider whether the loan qualifies for accounting as a loan or as an investment in a real estate development project. The Company has evaluated its real estate loans, where appropriate, for accounting treatment as loans versus real estate development projects, as required by ASC 310-10. For each loan, the Company has concluded that the characteristics and the facts and circumstances indicate that loan accounting treatment is appropriate. The following table summarizes our Notes receivable, net dollars in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Interest rate at ​ Balance Outstanding ​ March 31, March 31, December 31, ​ ​ 2021 ​ 2021 ​ 2020 Note due February 2021 (a) ​ N/A ​ $ — ​ $ 4,000 Note due May 2022 (b) ​ 8.00 % ​ 20,000 ​ ​ 20,000 Note due October 2022 (c) 4.75 % ​ 115,000 ​ ​ 115,000 Note due January 2023 (d) ​ 10.00 % ​ 20,885 ​ ​ 19,685 Notes Receivable ​ ​ ​ ​ 155,885 ​ ​ 158,685 Allowance for credit losses ​ ​ ​ ​ (679) ​ ​ (693) Total notes receivable, net ​ $ 155,206 ​ $ 157,992 (a) In May 2020, the Company entered into a promissory note with an unaffiliated third party with an aggregate commitment of $4.0 million, in connection with the sale of an operating community. In January 2021, the unaffiliated third party repaid the $4.0 million promissory note. (b) The Company has a secured note with an unaffiliated third party with an aggregate commitment of $20.0 million, all of which has been funded. The note is secured by a parcel of land and related land improvements. In September 2020, the developer defaulted on the loan. As a result of the default, in April 2021, UDR took title to the property pursuant to a deed in lieu of foreclosure. At that time, the Company reclassified the related balance as Real estate owned (c) The Company has a secured note with an unaffiliated third party with an aggregate commitment of $115.0 million, all of which has been funded. Interest payments are due when the loan matures. The note is secured by a first priority deed of trust on a 259 apartment home operating community in Bellevue, Washington, which was completed in 2020. When the note was funded, the Company also entered into a purchase option agreement and paid a deposit of $10.0 million, which gave the Company the option to acquire the community at a fixed price of $170.0 million. In August 2020, the Company exercised the purchase option. The purchase is expected to close in 2021. The deposit is generally nonrefundable other than due to a failure of closing conditions pursuant to the terms of the agreement. If the Company fails to close the purchase other than due to seller’s failure or other breaches in the purchase option agreement, per the terms of the agreement, the note will be modified to extend the maturity date to 10 years following the date the temporary certificate of occupancy was issued, which was July 2020. Upon modification, the loan would be interest only for the first three years and after such date payments will be based on a 30-year amortization schedule . (d) The Company has a secured note with an unaffiliated third party with an aggregate commitment of $22.0 million, of which $20.9 million has been funded, including $1.2 million funded during the three months ended March 31, 2021. Interest payments are due monthly. The note matures at the earliest of the following: (a) the closing of any private or public capital raising in the amount of $5.0 million or greater; (b) an acquisition; (c) acceleration in the event of default; or (d) January 2023. In January 2021, the terms of this secured note were amended to increase the aggregate commitment from $20.0 million to $22.0 million. Interest payments are due monthly and the maturity date of the note remains in January 2023. The Company recognized $1.9 million and $2.6 million of interest income for the notes receivable described above during the three months ended March 31, 2021 and 2020, respectively, none of which was related party interest. Interest income is included in Interest income and other income/(expense), net Comprehensive Income/(Loss) Comprehensive income/(loss), which is defined as the change in equity during each period from transactions and other events and circumstances from nonowner sources, including all changes in equity during a period except for those resulting from investments by or distributions to stockholders, is displayed in the accompanying Consolidated Statements of Comprehensive Income/(Loss). For the three months ended March 31, 2021 and 2020, the Company’s other comprehensive income/(loss) consisted of the gain/(loss) on derivative instruments that are designated as and qualify as cash flow hedges, (gain)/loss on derivative instruments reclassified from other comprehensive income/(loss) into earnings, and the allocation of other comprehensive income/(loss) to noncontrolling interests. The (gain)/loss on derivative instruments reclassified from other comprehensive income/(loss) is included in Interest expense Derivatives and Hedging Activity, Income Taxes Due to the structure of the Company as a REIT and the nature of the operations for the operating properties, no provision for federal income taxes has been provided for at UDR. Historically, the Company has generally incurred only state and local excise and franchise taxes. UDR has elected for certain consolidated subsidiaries to be treated as taxable REIT subsidiaries (“TRS”). Income taxes for our TRS are accounted for under the asset and liability method. Deferred tax assets and liabilities are recognized for future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax basis. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities from a change in tax rate is recognized in earnings in the period of the enactment date. The Company’s deferred tax assets/(liabilities) are generally the result of differing depreciable lives on capitalized assets, temporary differences between book and tax basis of assets and liabilities and timing of expense recognition for certain accrued liabilities. As of March 31, 2021 and December 31, 2020, UDR’s net deferred tax asset/(liability) was ($0.6) million and ($3.2) million, respectively, and are recorded in Accounts payable, accrued expenses and other liabilities GAAP defines a recognition threshold and measurement attribute for the financial statement recognition and measurement of a tax position taken or expected to be taken in a tax return. GAAP also provides guidance on derecognition, classification, interest and penalties, accounting for interim periods, disclosure and transition. The Company recognizes its tax positions and evaluates them using a two-step process. First, UDR determines whether a tax position is more likely than not (greater than 50 percent probability) to be sustained upon examination, including resolution of any related appeals or litigation processes, based on the technical merits of the position. Second, the Company will determine the amount of benefit to recognize and record the amount that is more likely than not to be realized upon ultimate settlement. The Company invests in assets that qualify for federal investment tax credits (“ITC”) through our TRS. An ITC reduces federal income taxes payable when qualifying depreciable property is acquired. The ITC is determined as a percentage of cost of the assets. The Company accounts for ITCs under the deferral method, under which the tax benefit from the ITC is deferred and amortized as a tax benefit into Tax (provision)/benefit, net Accounts payable, accrued expenses and other liabilities UDR had no material unrecognized tax benefit, accrued interest or penalties at March 31, 2021. UDR and its subsidiaries are subject to federal income tax as well as income tax of various state and local jurisdictions. The tax years 2017 through 2019 remain open to examination by tax jurisdictions to which we are subject. When applicable, UDR recognizes interest and/or penalties related to uncertain tax positions in Tax (provision)/benefit, net ​ Forward Sales Agreements ​ The Company utilizes forward sales agreements for the future issuance of its common stock. When the Company enters into a forward sales agreement, the contract requires the Company to sell its shares to a counterparty at a predetermined price at a future date. The net sales price and proceeds attained by the Company will be determined on the dates of settlement, with adjustments during the term of the contract for the Company’s anticipated dividends as well as for a daily interest factor that varies with changes in the federal funds rate. The Company generally has the ability to determine the dates and method of settlement (i.e., gross physical settlement, net share settlement or cash settlement), subject to certain conditions and the right of the counterparty to accelerate settlement under certain circumstances. ​ The Company accounts for the shares of common stock reserved for issuance upon settlement as equity in accordance with ASC 815-40, Contracts in Entity's Own Equity ​ The guidance establishes a two-step process for evaluating whether an equity-linked financial instrument is considered indexed to its own stock, first, evaluating the instrument’s contingent exercise provisions and second, evaluating the instrument’s settlement provisions. When entering into forward sales agreements, we determined that (i) none of the agreement’s exercise contingencies are based on observable markets or indices besides those related to the market for our own stock price; and (ii) none of the settlement provisions preclude the agreements from being indexed to our own stock. ​ Before the issuance of shares of common stock, upon physical or net share settlement of the forward sales agreements, the Company expects that the shares issuable upon settlement of the forward sales agreements will be reflected in its diluted income/(loss) per share calculations using the treasury stock method. Under this method, the number of shares of common stock used in calculating diluted income/(loss) per share is deemed to be increased by the excess, if any, of the number of shares of common stock that would be issued upon full physical settlement of the forward sales agreements over the number of shares of common stock that could be purchased by the Company in the open market (based on the average market price during the period) using the proceeds receivable upon full physical settlement (based on the adjusted forward sale price at the end of the reporting period). When the Company physically or net share settles any forward sales agreement, the delivery of shares of common stock would result in an increase in the number of weighted average common shares outstanding and dilution to basic income/(loss) per share. (See Note 8, Income/(Loss) per Share ​ Impact of COVID-19 Pandemic ​ The Company continues to closely monitor the impact of the COVID-19 pandemic on all aspects of its business. The extent of the pandemic’s effect on our operational and financial performance will depend on future developments, including the duration and intensity of the pandemic, the timing and effectiveness of COVID-19 vaccines, the duration of government measures to mitigate the pandemic and the success of government rental assistance programs, all of which continue to be uncertain and difficult to predict. ​ Given the uncertainty, we cannot predict the effect on future periods, but the adverse impact that could occur on the Company’s future financial condition, results of operations and cash flows could be material ​ During the three months ended March 31, 2021, the Company performed an analysis in accordance with the ASC 842, Leases, guidance to assess the collectibility of its operating lease receivables in light of the COVID-19 pandemic. This analysis included an assessment of collectibility of current and future rents and whether those lease payments were no longer probable of collection. In accordance with the leases guidance, if lease payments are no longer deemed to be probable over the life of the lease contract, we recognize revenue only when cash is received, and all existing contractual operating lease receivables and straight-line lease receivables are reserved. ​ As a result of its analysis, the Company reserved approximately $4.7 million of multifamily tenant lease receivables and approximately $0.8 million of retail tenant lease receivables for its wholly-owned communities and communities held by joint ventures for the three months ended March 31, 2021. In aggregate, the reserve is reflected as a $5.1 million reduction to Rental income and a $0.4 million reduction to Income/(loss) from unconsolidated entities on the Consolidated Statements of Operations for the three months ended March 31, 2021. The impact to deferred leasing commissions was not material for the three months ended March 31, 2021. ​ The Company did not recognize any other adjustments to the carrying amounts of assets or asset impairment charges due to the COVID-19 pandemic for the three months ended March 31, 2021.

REAL ESTATE OWNED

REAL ESTATE OWNED	3 Months Ended
	Mar. 31, 2021
REAL ESTATE OWNED
REAL ESTATE OWNED	3. REAL ESTATE OWNED Real estate assets owned by the Company consist of income producing operating properties, properties under development, land held for future development, and held for disposition properties. As of March 31, 2021, the Company owned and consolidated 150 communities in 13 states plus the District of Columbia totaling 48,363 apartment homes. The following table summarizes the carrying amounts for our real estate owned (at cost) as of March 31, 2021 and December 31, 2020 (dollars in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, December 31, ​ ​ 2021 ​ 2020 Land ​ $ 2,148,977 ​ $ 2,139,765 Depreciable property — held and used: ​ ​ Land improvements ​ 235,002 ​ 233,823 Building, improvements, and furniture, fixtures and equipment ​ 10,428,151 ​ 10,292,782 Real estate intangible assets ​ ​ 40,570 ​ ​ 40,570 Under development: ​ ​ Land and land improvements ​ 74,399 ​ 73,702 Building, improvements, and furniture, fixtures and equipment ​ 168,801 ​ 174,175 Real estate held for disposition: ​ ​ Land and land improvements ​ — ​ 15,184 Building, improvements, and furniture, fixtures and equipment ​ — ​ 101,471 Real estate owned ​ 13,095,900 ​ 13,071,472 Accumulated depreciation (a) ​ (4,730,021) ​ (4,605,366) Real estate owned, net ​ $ 8,365,879 ​ $ 8,466,106 (a) Accumulated depreciation is inclusive of $6.5 million of accumulated amortization related to real estate intangible assets. ​ Acquisitions In January 2021, the Company acquired a 300 apartment home operating community located in Franklin, Massachusetts for approximately $77.4 million. In connection with the acquisition, the Company assumed an above-market mortgage note payable secured by the community with an outstanding balance of approximately $51.8 million. The Company increased its real estate assets owned by approximately $82.0 million, recorded $2.0 million of in-place lease intangibles, and recorded a $6.6 million debt premium in connection with the above-market debt assumed. In April 2021, the Company acquired a 636 apartment home operating community located in Farmers Branch, Texas for approximately $110.0 million. ​ Dispositions ​ In February 2021, the Company sold an operating community located in Anaheim, California with a total of 386 apartment homes for gross proceeds of $156.0 million, resulting in a gain of approximately $50.8 million. ​ Other Activity Predevelopment, development, and redevelopment projects and related costs are capitalized and reported on the Consolidated Balance Sheets as Total real estate owned, net of accumulated depreciation support costs for personnel working on the capital projects. We use our professional judgment in determining whether such costs meet the criteria for capitalization or must be expensed as incurred. These costs are capitalized only during the period in which activities necessary to ready an asset for its intended use are in progress and such costs are incremental and identifiable to a specific activity to get the asset ready for its intended use. These costs, excluding the direct costs of development and redevelopment and capitalized interest, for the three months ended March 31, 2021 and 2020, were $4.6 million and $6.9 million, respectively. Total capitalized interest was $2.1 million and $1.4 million for the three months ended March 31, 2021 and 2020, respectively. As each apartment home in a capital project is completed and becomes available for lease-up, the Company ceases capitalization on the related portion of the costs and depreciation commences over the estimated useful life. We record impairment losses on long-lived assets used in operations when events and circumstances indicate that the assets might be impaired and the undiscounted cash flows estimated to be generated by the future operation and disposition of those assets are less than the net book value of those assets. Our cash flow estimates are based upon historical results adjusted to reflect our best estimate of future market and operating conditions and our estimated holding periods. The net book value of impaired assets is reduced to fair value. Our estimates of fair value represent our best estimate based upon Level 3 inputs such as industry trends and reference to market rates and transactions. The Company did not recognize any impairments in the value of its long-lived assets during the three months ended March 31, 2021 and 2020. In connection with the acquisition of certain properties, the Company agreed to pay certain of the tax liabilities of certain contributors if the Company sells one or more of the properties contributed in a taxable transaction prior to the expiration of specified periods of time following the acquisition. The Company may, however, sell, without being required to pay any tax liabilities, any of such properties in a non-taxable transaction, including, but not limited to, a tax-deferred Section 1031 exchange. Further, the Company has agreed to maintain certain debt that may be guaranteed by certain contributors for specified periods of time following the acquisition. The Company, however, has the ability to refinance or repay guaranteed debt or to substitute new debt if the debt and the guaranty continue to satisfy certain conditions.

VARIABLE INTEREST ENTITIES

VARIABLE INTEREST ENTITIES	3 Months Ended
	Mar. 31, 2021
VARIABLE INTEREST ENTITIES
VARIABLE INTEREST ENTITIES	4. VARIABLE INTEREST ENTITIES The Company has determined that the Operating Partnership and DownREIT Partnership are VIEs as the limited partners lack substantive kick-out rights and substantive participating rights. The Company has concluded that it is the primary beneficiary of, and therefore consolidates, the Operating Partnership and DownREIT Partnership based on its role as the sole general partner of the Operating Partnership and DownREIT Partnership. The Company’s role as community manager and its equity interests give us the power to direct the activities that most significantly impact the economic performance and the obligation to absorb potentially significant losses or the right to receive potentially significant benefits of the Operating Partnership and DownREIT Partnership.

JOINT VENTURES AND PARTNERSHIPS

JOINT VENTURES AND PARTNERSHIPS	3 Months Ended
	Mar. 31, 2021
JOINT VENTURES AND PARTNERSHIPS
JOINT VENTURES AND PARTNERSHIPS	5. JOINT VENTURES AND PARTNERSHIPS UDR has entered into joint ventures and partnerships with unrelated third parties to own, operate, acquire, renovate, develop, redevelop, dispose of, and manage real estate assets that are either consolidated and included in Real estate owned Investment in and advances to unconsolidated joint ventures, net UDR’s joint ventures and partnerships are funded with a combination of debt and equity. Our losses are typically limited to our investment and except as noted below, the Company does not guarantee any debt, capital payout or other obligations associated with our joint ventures and partnerships. The Company recognizes earnings or losses from our investments in unconsolidated joint ventures and partnerships consisting of our proportionate share of the net earnings or losses of the joint ventures and partnerships. In addition, we may earn fees for providing management services for the communities held by the unconsolidated joint ventures and partnerships. The following table summarizes the Company’s investment in and advances to unconsolidated joint ventures and partnerships, net, which are accounted for under the equity method of accounting as of March 31, 2021 and December 31, 2020 (dollars in thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Number of ​ Number of ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Operating ​ Apartment ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Income/(loss) from investments ​ ​ ​ ​ Communities ​ Homes ​ Investment at ​ UDR’s Ownership Interest ​ ​ Three Months Ended ​ Location of March 31, March 31, March 31, December 31, ​ March 31, ​ December 31, ​ March 31, Joint Ventures Properties 2021 2021 2021 2020 ​ 2021 ​ 2020 ​ 2021 2020 Operating: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ UDR/MetLife I ​ Los Angeles, CA ​ 1 ​ 150 ​ $ 26,001 ​ $ 26,426 ​ 50.0 % ​ 50.0 % ​ $ (475) ​ $ (454) UDR/MetLife II Various 7 1,250 ​ 186,312 ​ 151,353 ​ 50.0 % ​ 50.0 % ​ ​ (2,684) ​ ​ (91) Other UDR/MetLife Joint Ventures (a) Various 5 1,437 ​ 78,155 ​ 82,072 ​ 50.6 % ​ 50.6 % ​ ​ (3,382) ​ ​ (1,811) West Coast Development Joint Ventures (b) ​ Los Angeles, CA ​ — ​ — ​ ​ 311 ​ ​ 30,080 ​ 47.0 % ​ 47.0 % ​ ​ 2,486 ​ ​ (77) Investment in and advances to unconsolidated joint ventures, net, before preferred equity investments and real estate technology investments ​ $ 290,779 ​ $ 289,931 ​ ​ ​ ​ $ (4,055) ​ $ (2,433) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Investment at ​ Three Months Ended Developer Capital Program ​ ​ Years To ​ UDR March 31, December 31, March 31, and Real Estate Technology Investments (c) Location Rate Maturity ​ Commitment (d) 2021 2020 2021 2020 Preferred equity investments: ​ ​ ​ ​ ​ ​ ​ ​ ​ 1532 Harrison ​ San Francisco, CA ​ 11.0 % 1.2 ​ $ 24,645 ​ $ 35,069 ​ $ 34,135 ​ $ 929 ​ $ 836 1200 Broadway (e) (f) ​ Nashville, TN ​ 8.0 % 1.5 ​ ​ 55,558 ​ ​ 70,709 ​ ​ 69,330 ​ ​ 1,372 ​ ​ 1,281 Junction ​ Santa Monica, CA ​ 12.0 % 1.3 ​ ​ 8,800 ​ ​ 12,049 ​ ​ 11,699 ​ ​ 350 ​ ​ 314 1300 Fairmount (f) ​ Philadelphia, PA ​ 8.5 % 2.4 ​ ​ 51,393 ​ ​ 60,799 ​ ​ 59,544 ​ ​ 1,255 ​ ​ 1,166 Essex ​ Orlando, FL ​ 12.5 % 2.4 ​ ​ 12,886 ​ ​ 17,292 ​ ​ 16,770 ​ ​ 522 ​ ​ 466 Modera Lake Merritt (f) ​ Oakland, CA ​ 9.0 % 3.0 ​ ​ 27,250 ​ ​ 31,619 ​ ​ 30,928 ​ ​ 691 ​ ​ 574 Thousand Oaks (f) ​ Thousand Oaks, CA ​ 9.0 % 3.8 ​ ​ 20,059 ​ ​ 21,278 ​ ​ 17,919 ​ ​ 438 ​ ​ 24 Vernon Boulevard (f) ​ Queens, NY ​ 13.0 % 4.3 ​ ​ 40,000 ​ ​ 43,737 ​ ​ 42,360 ​ ​ 1,372 ​ ​ — Makers Rise (f) (g) ​ Herndon, VA ​ 9.0 % 4.7 ​ ​ 30,208 ​ ​ 7,070 ​ ​ — ​ ​ 96 ​ ​ — 121 at Watters (f) (h) ​ Allen, TX ​ 9.0 % 5.0 ​ ​ 19,846 ​ ​ 12 ​ ​ — ​ ​ 2 ​ ​ — Real estate technology investments: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ RETV I ​ N/A ​ N/A ​ N/A ​ ​ 18,000 ​ ​ 22,641 ​ ​ 20,587 ​ ​ 2,051 ​ ​ (150) RETV II ​ N/A ​ N/A ​ N/A ​ $ 16,500 ​ ​ 2,184 ​ ​ 2,283 ​ ​ (101) ​ ​ — Total Preferred Equity Investments and Real Estate Technology Investments ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 324,459 ​ ​ 305,555 ​ ​ 8,977 ​ ​ 4,511 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Sold joint ventures and other investments in prior year ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ — ​ ​ — ​ ​ — ​ ​ 1,289 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total Joint Ventures and Developer Capital Program and Real Estate Technology Investments, net (a) ​ ​ ​ ​ $ 615,238 ​ $ 595,486 ​ $ 4,922 $ 3,367 (a) As of March 31, 2021 and December 31, 2020, the Company’s negative investment in 13 th and Market Properties LLC of $4.9 million and $4.7 million, respectively, is included in Other UDR/MetLife Joint Ventures in the table above and recorded in Accounts payable, accrued expenses, and other liabilities on the Consolidated Balance Sheet. (b) In J anuary 2021, the joint venture sold its remaining community, a 293 home operating community located in Los Angeles, California, for a sales price of approximately $121.0 million. As a result, the Company recorded a gain on the sale of approximately $2.5 million . (c) The Developer Capital Program is the program through which the Company makes investments, including preferred equity investments, mezzanine loans or other structured investments that may receive a fixed yield on the investment and may include provisions pursuant to which the Company participates in the increase in value of the property upon monetization of the applicable property and/or holds fixed price purchase options. (d) Represents UDR’s maximum funding commitment only and therefore excludes other activity such as income from investments. (e) In April 2021, the balance was paid down by $12.5 million and the Company’s preferred return increased to 12.25%. The Company's preferred return will revert to 8.0% in February 2022 if no capital events occur prior to that date. (f) The Company’s preferred equity investment receives a variable percentage of the value created from the project upon a capital or liquidating event. (g) In January 2021, the Company entered into a joint venture agreement with an unaffiliated joint venture partner to develop and operate a 356 apartment home community in Herndon, Virginia. The Company’s preferred equity investment of $30.2 million earns a preferred return of 9.0% per annum and receives a variable percentage of the value created from the project upon a capital or liquidating event. The unaffiliated joint venture partner is the managing member of the joint venture and the developer of the community. The Company has concluded that it does not control the joint venture and accounts for it under the equity method of accounting . (h) In March 2021, the Company entered into a joint venture agreement with an unaffiliated joint venture partner to develop and operate a 469 apartment home community in Allen, Texas. The Company’s preferred equity investment of $19.8 million earns a preferred return of 9.0% per annum and receives a variable percentage of the value created from the project upon a capital or liquidating event. The unaffiliated joint venture partner is the managing member of the joint venture and the developer of the community. The Company has concluded that it does not control the joint venture and accounts for it under the equity method of accounting . ​ As of March 31, 2021 and December 31, 2020, the Company had deferred fees of $9.2 million and $8.4 million, respectively, which will be recognized through earnings over the weighted average life of the related properties, upon the disposition of the properties to a third party, or upon completion of certain development obligations. The Company recognized management fees of $1.6 million and $ 1.4 million for the three months ended March 31, 2021 and 2020, respectively, for management of the communities held by the joint ventures and partnerships. The management fees are included in Joint venture management and other fees on the Consolidated Statements of Operations. The Company may, in the future, make additional capital contributions to certain of our joint ventures and partnerships should additional capital contributions be necessary to fund acquisitions or operations. We consider various factors to determine if a decrease in the value of our Investment in and advances to unconsolidated joint ventures, net Combined summary balance sheets relating to the unconsolidated joint ventures’ and partnerships’ (not just our proportionate share) are presented below as of March 31, 2021 and December 31, 2020 ( dollars in thousands ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, ​ December 31, ​ 2021 2020 Total real estate, net $ 2,111,478 $ 1,904,805 Real estate assets held for sale ​ — ​ 88,458 Cash and cash equivalents ​ 28,120 ​ 22,278 Other assets ​ ​ 162,316 ​ 150,894 Total assets $ 2,301,914 $ 2,166,435 ​ ​ ​ ​ ​ ​ ​ Third party debt, net ​ $ 1,193,327 ​ $ 1,188,710 Liabilities held for sale ​ — ​ 55,440 Accounts payable and accrued liabilities ​ ​ 71,859 ​ ​ 40,556 Total liabilities ​ 1,265,186 ​ 1,284,706 Total equity $ 1,036,728 $ 881,729 ​ Combined summary financial information relating to the unconsolidated joint ventures’ and partnerships’ operations (not just our proportionate share) is presented below for the three months ended March 31, 2021 and 2020 ( dollars in thousands : ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ ​ March 31, ​ 2021 2020 Total revenues $ 32,137 $ 41,314 Property operating expenses ​ 17,110 ​ 15,297 Real estate depreciation and amortization ​ 16,453 ​ 16,243 Gain/(loss) on sale of property ​ ​ 34,757 ​ ​ — Operating income/(loss) ​ 33,331 ​ ​ 9,774 Interest expense ​ (12,134) ​ (10,347) Net realized/unrealized gain/(loss) on held investments ​ ​ 8,488 ​ ​ — Other income/(loss) ​ ​ (1,657) ​ ​ (8) Net income/(loss) $ 28,028 $ (581) ​

LEASES

LEASES	3 Months Ended
	Mar. 31, 2021
LEASES
LEASES	6. LEASES Lessee - Ground Leases UDR owns six communities that are subject to ground leases, under which UDR is the lessee, expiring between 2043 and 2103, inclusive of extension options we are reasonably certain will be exercised. All of these leases are classified as operating leases through the lease term expiration based on our election of the practical expedient provided by the leasing standard. Rental expense for lease payments related to operating leases is recognized on a straight-line basis over the remaining lease term. We currently do not hold any finance leases. The Company also elected the short-term lease exception provided by the leasing standard and therefore only recognizes right-of-use assets and lease liabilities for leases with a term greater than one year. No leases qualified for the short-term lease exception during the three months ended March 31, 2021 and 2020. As of March 31, 2021 and December 31, 2020, the Operating lease right-of-use assets Operating lease liabilities Operating lease right-of-use assets Operating lease liabilities As the discount rate implicit in the leases was not readily determinable, we determined the discount rate for these leases utilizing the Company’s incremental borrowing rate at a portfolio level, adjusted for the remaining lease term, and the form of underlying collateral. The weighted average remaining lease term for these leases was 43.8 years and 43.9 years at March 31, 2021 and December 31, 2020, respectively, and the weighted average discount rate was 5.0% at both March 31, 2021 and December 31, 2020. Future minimum lease payments and total operating lease liabilities from our ground leases as of March 31, 2021 are as follows (dollars in thousands): ​ ​ ​ ​ ​ ​ Ground Leases 2021 ​ $ 9,331 2022 ​ ​ 12,442 2023 ​ ​ 12,442 2024 ​ ​ 12,442 2025 ​ ​ 12,442 Thereafter ​ ​ 442,778 Total future minimum lease payments (undiscounted) ​ ​ 501,877 Difference between future undiscounted cash flows and discounted cash flows ​ ​ (307,048) Total operating lease liabilities (discounted) ​ $ 194,829 ​ For purposes of recognizing our ground lease contracts, the Company uses the minimum lease payments, if stated in the agreement. For ground lease agreements where there is a rent reset provision based on a change in an index or a rate (i.e., changes in fair market rental rates or changes in the consumer price index) but that does not include a specified minimum lease payment, the Company uses the current rent over the remainder of the lease term. If there is a contingency upon which some or all of the variable lease payments that will be paid over the remainder of the lease term are based, which is resolved such that those payments now meet the definition of lease payments, the Company will remeasure the right-of-use asset and lease liability on the reset date. The components of operating lease expenses were as follows (dollars in thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended March 31, ​ ​ 2021 ​ 2020 Lease expense: ​ ​ ​ ​ ​ ​ Contractual lease expense ​ $ 3,230 ​ $ 3,170 Variable lease expense (a) ​ ​ 29 ​ ​ 43 Total operating lease expense (b)(c) ​ $ 3,259 ​ $ 3,213 (a) Variable lease expense includes adjustments such as changes in the consumer price index and payments based on a percentage of income of the lessee. (b) Lease expense is reported within the line item Other operating expenses on the Consolidated Statements of Operations. (c) For the three months ended March 31, 2021, Operating lease right-of-use assets and Operating lease liabilities amortized by $0.8 million and $0.8 million, respectively. For the three months ended March 31, 2020, Operating lease right-of-use assets and Operating lease liabilities amortized by $0.8 million and $0.7 million, respectively. Due to the net impact of the amortization, the Company recorded less than $0.1 million and $0.1 million of total operating lease expense during the three months ended March 31, 2021 and 2020, respectively. ​ Lessor - Apartment Home, Retail and Commercial Space Leases ​ UDR’s communities and retail and commercial space are leased to tenants under operating leases. As of March 31, 2021, our apartment home leases generally have initial terms of 12 months or less and represent approximately 98.6% of our total lease revenue. As of March 31, 2021, our retail and commercial space leases generally have initial terms of between 5 and 15 years and represent approximately 1.4% of our total lease revenue. Our apartment home leases are generally renewable at the end of the lease term, subject to potential increases in rental rates, and our retail and commercial space leases generally have renewal options, subject to associated increases in rental rates due to market based or fixed price renewal options and certain other conditions. (See Note 14, Reportable Segments ​ Future minimum lease payments from our retail and commercial leases as of March 31, 2021 are as follows (dollars in thousands): ​ ​ ​ ​ ​ ​ Retail and Commercial Leases 2021 ​ $ 18,056 2022 ​ ​ 23,450 2023 ​ ​ 21,645 2024 ​ ​ 19,879 2025 ​ ​ 16,758 Thereafter ​ ​ 71,357 Total future minimum lease payments (a) ​ $ 171,145 (a) Certain of our leases with retail and commercial tenants provide for the payment by the lessee of additional variable rent based on a percentage of the tenant’s revenue. The amounts shown in the table above do not include these variable percentage rents. The Company recorded variable percentage rents of $0.1 million and $0.1 million during the three months ended March 31, 2021 and 2020, respectively.

SECURED AND UNSECURED DEBT, NET

SECURED AND UNSECURED DEBT, NET	3 Months Ended
	Mar. 31, 2021
SECURED AND UNSECURED DEBT, NET
SECURED AND UNSECURED DEBT, NET	7. SECURED AND UNSECURED DEBT, NET The following is a summary of our secured and unsecured debt at March 31, 2021 and December 31, 2020 ( dollars in thousands ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Principal Outstanding ​ As of March 31, 2021 ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ Weighted ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Average ​ Average ​ Number of ​ ​ March 31, ​ December 31, ​ Interest ​ Years to ​ Communities ​ 2021 2020 Rate Maturity Encumbered Secured Debt: ​ ​ ​ ​ ​ ​ ​ Fixed Rate Debt ​ ​ Mortgage notes payable (a) ​ $ 876,080 ​ $ 824,550 3.37 % 7.0 12 Deferred financing costs and other non-cash adjustments (b) ​ 16,162 ​ 10,665 Total fixed rate secured debt, net ​ 892,242 ​ 835,215 3.37 % 7.0 12 Variable Rate Debt ​ ​ Tax-exempt secured notes payable (c) ​ 27,000 ​ 27,000 0.77 % 11.0 1 Deferred financing costs ​ (65) ​ (68) Total variable rate secured debt, net ​ 26,935 ​ 26,932 0.77 % 11.0 1 Total Secured Debt, net ​ 919,177 ​ 862,147 3.29 % 7.1 13 Unsecured Debt: ​ ​ Variable Rate Debt ​ ​ Borrowings outstanding under unsecured credit facility due January 2023 (d) (o) ​ — ​ — — % 1.8 Borrowings outstanding under unsecured commercial paper program due April 2021 (e) (o) ​ ​ 210,000 ​ ​ 190,000 ​ 0.26 % 0.1 ​ ​ Borrowings outstanding under unsecured working capital credit facility due January 2022 ​ 17,813 ​ 28,024 0.94 % 0.8 Term Loan due September 2023 (d) (o) ​ 35,000 ​ 35,000 1.02 % 2.5 Fixed Rate Debt ​ ​ Term Loan due September 2023 (d) (o) ​ ​ 315,000 ​ 315,000 1.07 % 2.5 ​ ​ 8.50% Debentures due September 2024 ​ 15,644 ​ 15,644 8.50 % 3.5 4.00% Medium-Term Notes due October 2025 (net of discounts of $0 and $327, respectively) (g) (o) ​ — ​ 299,673 — % — 2.95% Medium-Term Notes due September 2026 (h) (o) ​ 300,000 ​ 300,000 2.89 % 5.4 3.50% Medium-Term Notes due July 2027 (net of discounts of $441 and $458, respectively) (i) (o) ​ ​ 299,559 ​ ​ 299,542 ​ 4.03 % 6.3 ​ ​ 3.50% Medium-Term Notes due January 2028 (net of discounts of $806 and $835, respectively) (o) ​ ​ 299,194 ​ ​ 299,165 ​ 3.50 % 6.8 ​ ​ 4.40% Medium-Term Notes due January 2029 (net of discounts of $5 and $5, respectively) (j) (o) ​ ​ 299,995 ​ ​ 299,995 ​ 4.27 % 7.8 ​ ​ 3.20% Medium-Term Notes due January 2030 (net of premiums of $12,070 and $12,412, respectively) (k) (o) ​ ​ 612,070 ​ ​ 612,412 ​ 3.32 % 8.8 ​ ​ 3.00% Medium-Term Notes due August 2031 (net of discounts of $1,003 and $1,027, respectively) (l) (o) ​ ​ 398,997 ​ ​ 398,973 ​ 3.01 % 10.4 ​ ​ 2.10% Medium-Term Notes due August 2032 (net of discounts of $399 and $408, respectively) (o) ​ ​ 399,601 ​ ​ 399,592 ​ 2.10 % 11.3 ​ ​ 1.90% Medium-Term Notes due March 2033 (net of discounts of $1,440 and $1,471, respectively) (o) ​ ​ 348,560 ​ ​ 348,529 ​ 1.90 % 12.0 ​ ​ 2.10% Medium-Term Notes due June 2033 (net of discounts of $1,215 and $0, respectively) (m) (o) ​ ​ 298,785 ​ ​ — ​ 2.10 % 12.2 ​ ​ 3.10% Medium-Term Notes due November 2034 (net of discounts of $1,199 and $1,221, respectively) (n) (o) ​ ​ 298,801 ​ ​ 298,779 ​ 3.13 % 13.6 ​ ​ Other ​ 9 ​ 10 Deferred financing costs ​ (27,030) ​ (25,937) Total Unsecured Debt, net ​ 4,121,998 ​ 4,114,401 2.72 % 8.4 Total Debt, net ​ $ 5,041,175 ​ $ 4,976,548 2.84 % 8.2 ​ For purposes of classification of the above table, variable rate debt with a derivative financial instrument designated as a cash flow hedge is deemed as fixed rate debt due to the Company having effectively established a fixed interest rate for the underlying debt instrument. Our secured debt instruments generally feature either monthly interest and principal or monthly interest-only payments with balloon payments due at maturity. As of March 31, 2021, secured debt encumbered $1.5 billion or 11.2% of UDR’s total real estate owned based upon gross book value ($11.6 billion or 88.8% of UDR’s real estate owned based on gross book value is unencumbered). (a) In January 2021, the Company assumed a fixed rate mortgage note payable with an outstanding balance of $51.8 million and a fair value of $58.4 million in connection with the acquisition of an operating property located in Franklin, Real Estate Owned . ​ The Company will from time to time acquire properties subject to fixed rate debt instruments. In those situations, the Company records the debt at its estimated fair value and amortizes any difference between the fair value and par value to interest expense over the life of the underlying debt instrument. (b) Interest expense ​ (c) (d) six-month extension options, subject to certain conditions. The Term Loan has a scheduled maturity date of September 30, 2023. Based on the Company’s current credit rating, the Revolving Credit Facility has an interest rate equal to LIBOR plus a margin of 82.5 basis points and a facility fee of 15 basis points, and the Term Loan has an interest rate equal to LIBOR plus a margin of 90 basis points. Depending on the Company’s credit rating, the margin under the Revolving Credit Facility ranges from 75 to 145 basis points, the facility fee ranges from 10 to 30 basis points, and the margin under the Term Loan ranges from 80 to 165 basis points. In November 2020, the Company entered into three interest rate swaps, which became effective in January 2021, to hedge against interest rate risk on the Term Loan until July 2022. The all-in weighted average interest rate, inclusive of the impact of the interest rate swaps, was 1.07% . ​ The Credit Agreement contains customary representations and warranties and financial and other affirmative and negative covenants. The Credit Agreement also includes customary events of default, in certain cases subject to customary periods to cure. The occurrence of an event of default, following the applicable cure period, would permit the lenders to, among other things, declare the unpaid principal, accrued and unpaid interest and all other amounts payable under the Credit Agreement to be immediately due and payable. The following is a summary of short-term bank borrowings under the Revolving Credit Facility at March 31, 2021 and December 31, 2020 (dollars in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, December 31, ​ ​ 2021 2020 ​ Total revolving credit facility ​ $ 1,100,000 ​ $ 1,100,000 ​ Borrowings outstanding at end of period (1) ​ — ​ — ​ Weighted average daily borrowings during the period ended ​ — ​ 42,186 ​ Maximum daily borrowings during the period ended ​ — ​ 375,000 ​ Weighted average interest rate during the period ended ​ — % 1.4 % Interest rate at end of the period ​ — % — % (1) Excludes $2.3 million and $2.8 million of letters of credit at March 31, 2021 and December 31, 2020, respectively . (e) The following is a summary of short-term bank borrowings under the unsecured commercial paper program at March 31, 2021 and December 31, 2020 (dollars in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, December 31, ​ ​ 2021 ​ 2020 Total unsecured commercial paper program $ 500,000 ​ $ 500,000 ​ Borrowings outstanding at end of period ​ 210,000 ​ 190,000 ​ Weighted average daily borrowings during the period ended ​ 191,389 ​ 227,090 ​ Maximum daily borrowings during the period ended ​ 340,000 ​ 500,000 ​ Weighted average interest rate during the period ended ​ 0.3 % 0.9 % Interest rate at end of the period ​ 0.3 % 0.3 % ​ In April 2021, the entire $210.0 million of outstanding unsecured commercial paper as of March 31, 2021 was repaid at maturity with additional proceeds of unsecured commercial paper with maturity dates in May 2021 and proceeds under the Working Capital Credit Facility. (f) 82.5 basis points. Depending on the Company’s credit rating, the margin ranges from 75 to 145 basis points. The following is a summary of short-term bank borrowings under the Working Capital Credit Facility at March 31, 2021 and December 31, 2020 (dollars in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, December 31, ​ ​ 2021 ​ 2020 Total working capital credit facility ​ $ 75,000 ​ $ 75,000 ​ Borrowings outstanding at end of period ​ 17,813 ​ 28,024 ​ Weighted average daily borrowings during the period ended ​ 7,438 ​ 20,132 ​ Maximum daily borrowings during the period ended ​ 37,560 ​ 54,974 ​ Weighted average interest rate during the period ended ​ 0.9 % 1.4 % Interest rate at end of the period ​ 0.9 % 1.0 % ​ (g) (h) (i) (j) (k) The all-in weighted average interest rate, inclusive of the impact of the forward starting swaps and treasury locks, was 3.32% . (l) (m) . (n) . (o) The aggregate maturities, including amortizing principal payments on secured and unsecured debt, of total debt for the next ten calendar years subsequent to March 31, 2021 are as follows (dollars in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total Fixed Total Variable Total Total Total Year ​ Secured Debt ​ Secured Debt ​ Secured Debt ​ Unsecured Debt ​ Debt 2021 ​ $ 827 ​ $ — ​ $ 827 ​ $ 210,000 (a) $ 210,827 2022 ​ ​ 1,140 ​ ​ — ​ ​ 1,140 ​ ​ 17,813 ​ ​ 18,953 2023 ​ 1,183 ​ — ​ 1,183 ​ 350,000 ​ 351,183 2024 ​ 96,028 ​ — ​ 96,028 ​ 15,644 ​ 111,672 2025 ​ 174,043 ​ — ​ 174,043 ​ — ​ 174,043 2026 ​ 51,963 ​ — ​ 51,963 ​ 300,000 ​ 351,963 2027 ​ 2,045 ​ — ​ 2,045 ​ 300,000 ​ 302,045 2028 ​ 123,435 ​ — ​ 123,435 ​ 300,000 ​ 423,435 2029 ​ 191,986 ​ — ​ 191,986 ​ 300,000 ​ 491,986 2030 ​ 72,500 ​ — ​ 72,500 ​ 600,000 ​ 672,500 Thereafter ​ 160,930 ​ 27,000 ​ 187,930 ​ 1,750,000 ​ 1,937,930 Subtotal ​ 876,080 ​ 27,000 ​ 903,080 ​ 4,143,457 ​ 5,046,537 Non-cash (b) ​ 16,162 ​ (65) ​ 16,097 ​ (21,459) ​ (5,362) Total ​ $ 892,242 ​ $ 26,935 ​ $ 919,177 ​ $ 4,121,998 ​ $ 5,041,175 (a) All unsecured debt due in the remainder of 2021 is related to the Company’s commercial paper program. (b) Includes the unamortized balance of fair market value adjustments, premiums/discounts and deferred financing costs . The Company amortized $1.2 million and $1.0 million, respectively, during the three months ended March 31, 2021 and 2020, of deferred financing costs into Interest expense. We were in compliance with the covenants of our debt instruments at March 31, 2021.

INCOME_(LOSS) PER SHARE

INCOME/(LOSS) PER SHARE	3 Months Ended
	Mar. 31, 2021
INCOME/(LOSS) PER SHARE
INCOME/(LOSS) PER SHARE	8. INCOME/(LOSS) PER SHARE The following table sets forth the computation of basic and diluted income/(loss) per share for the periods presented (dollars and shares in thousands, except per share data): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ ​ ​ March 31, ​ ​ 2021 2020 ​ Numerator for income/(loss) per share: ​ ​ ​ ​ ​ ​ Net income/(loss) ​ $ 3,274 ​ $ 5,540 ​ Net (income)/loss attributable to redeemable noncontrolling interests in the Operating Partnership and DownREIT Partnership ​ (154) ​ (313) ​ Net (income)/loss attributable to noncontrolling interests ​ (16) ​ (6) ​ Net income/(loss) attributable to UDR, Inc. ​ 3,104 ​ 5,221 ​ Distributions to preferred stockholders — Series E (Convertible) ​ (1,056) ​ (1,066) ​ Income/(loss) attributable to common stockholders - basic and diluted ​ $ 2,048 ​ $ 4,155 ​ ​ ​ ​ ​ ​ ​ ​ ​ Denominator for income/(loss) per share: ​ ​ ​ Weighted average common shares outstanding ​ 296,800 ​ 294,731 ​ Non-vested restricted stock awards ​ (263) ​ (274) ​ Denominator for basic income/(loss) per share ​ 296,537 ​ 294,457 ​ Incremental shares issuable from assumed conversion of unvested LTIP Units and unvested restricted stock ​ 489 ​ 703 ​ Denominator for diluted income/(loss) per share ​ 297,026 ​ 295,160 ​ ​ ​ ​ ​ ​ ​ ​ ​ Income/(loss) per weighted average common share: ​ ​ ​ Basic ​ $ 0.01 ​ $ 0.01 ​ Diluted ​ $ 0.01 ​ $ 0.01 ​ ​ Basic income/(loss) per common share is computed based upon the weighted average number of common shares outstanding. Diluted income/(loss) per common share is computed based upon the weighted average number of common shares outstanding plus the common shares issuable from the assumed conversion of the OP Units and DownREIT Units, convertible preferred stock, stock options, unvested long-term incentive plan units (“LTIP Units”), unvested restricted stock and continuous equity program forward sales agreements. Only those instruments having a dilutive impact on our basic income/(loss) per share are included in diluted income/(loss) per share during the periods. For the three months ended March 31, 2021 and 2020, the effect of the conversion of the OP Units, DownREIT Units and the Company’s Series E preferred stock was not dilutive and therefore not included in the above calculation. In July 2017, the Company entered into an ATM sales agreement under which the Company may offer and sell up to 20.0 million shares of its common stock, from time to time, to or through its sales agents and may enter into separate forward sales agreements to or through its forward purchasers. Upon entering into the ATM sales agreement, the Company simultaneously terminated the sales agreement for its prior at-the-market equity offering program, which was entered into in April 2017, which replaced the prior at-the-market equity offering program entered into in April 2012. During the three months ended March 31, 2021, the Company did not sell any shares of common stock through its ATM program, other than the forward sales described below. As of March 31, 2021, we had 9.6 million shares of common stock available for future issuance under the ATM program, including an aggregate of 2.3 million shares subject to the forward sales agreements described below. In connection with any forward sales agreement under the Company’s ATM program, the relevant forward purchasers will borrow from third parties and, through the relevant sales agent, acting in its role as forward seller, sell a number of shares of the Company’s common stock equal to the number of shares underlying the agreement. The Company does not initially receive any proceeds from any sale of borrowed shares by the forward seller. ​ During the three months ended March 31, 2021, the Company entered into forward sales agreements under its ATM program for a total of 2.3 million shares of common stock at a weighted average initial forward price per share of $43.85. The actual forward price per share to be received by the Company upon settlement will be determined on the applicable settlement date based on adjustments made to the initial forward price to reflect the then-current federal funds rate and the amount of dividends paid to holders of UDR common stock over the term of the forward sales agreement. As of March 31, 2021, no shares under the forward sales agreements have been settled. The final dates by which shares sold under the forward sales agreements must be settled range between February 23, 2022 and March 15, 2022. ​ In March 2021, the Company entered into forward sale agreements to sell 7.0 million shares of its common stock at an initial forward price per share of $43.51. The actual forward price per share to be received by the Company upon settlement will be determined on the applicable settlement date based on adjustments made to the initial forward price to reflect the then-current federal funds rate and the amount of dividends paid to holders of UDR common stock over the term of the forward sales agreement. As of March 31, 2021, no shares under the forward sale agreements have been settled. The final date by which shares sold under the forward sale agreements must be settled is March 29, 2022. ​ The Company generally has the ability to determine the dates and method of settlement (i.e., gross physical settlement, net share settlement or cash settlement), subject to certain conditions and the right of the counterparty to accelerate settlement under certain circumstances. The Company currently expects to fully physically settle each forward sales agreement with the relevant forward purchaser on one or more dates specified by the Company on or prior to the maturity date of that particular forward sales agreement, in which case the Company expects to receive aggregate net cash proceeds at settlement equal to the number of shares underlying the particular forward sales agreement multiplied by the relevant forward sale price. However, subject to certain exceptions, the Company may also elect, in its discretion, to cash settle or net share settle a particular forward sales agreement, in which case the Company may not receive any proceeds (in the case of cash settlement) or will not receive any proceeds (in the case of net share settlement), and the Company may owe cash (in the case of cash settlement) or shares of UDR common stock (in the case of net share settlement) to the relevant forward purchaser. ​ The following table sets forth the additional shares of common stock outstanding, by equity instrument, if converted to common stock for each of the three months ended March 31, 2021 and 2020 (in thousands) ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ ​ ​ March 31, ​ ​ ​ 2021 ​ 2020 ​ OP/DownREIT Units 22,398 22,228 Convertible preferred stock 2,918 3,011 Unvested LTIP Units and unvested restricted stock 489 703 ​

NONCONTROLLING INTERESTS

NONCONTROLLING INTERESTS	3 Months Ended
	Mar. 31, 2021
NONCONTROLLING INTERESTS
NONCONTROLLING INTERESTS	9. NONCONTROLLING INTERESTS Redeemable Noncontrolling Interests in the Operating Partnership and DownREIT Partnership Interests in the Operating Partnership and the DownREIT Partnership held by limited partners are represented by OP Units and DownREIT Units, respectively. The income is allocated to holders of OP Units/DownREIT Units based upon net income attributable to common stockholders and the weighted average number of OP Units/DownREIT Units outstanding to total common shares plus OP Units/DownREIT Units outstanding during the period. Capital contributions, distributions, and profits and losses are allocated to noncontrolling interests in accordance with the terms of the partnership agreements of the Operating Partnership and the DownREIT Partnership. Limited partners of the Operating Partnership and the DownREIT Partnership have the right to require such partnership to redeem all or a portion of the OP Units/DownREIT Units held by the limited partner at a redemption price equal to and in the form of the Cash Amount (as defined in the partnership agreement of the Operating Partnership or the DownREIT Partnership, as applicable), provided that such OP Units/DownREIT Units have been outstanding for at least one year, subject to certain exceptions. UDR, as the general partner of the Operating Partnership and the DownREIT Partnership may, in its sole discretion, purchase the OP Units/DownREIT Units by paying to the limited partner either the Cash Amount or the REIT Share Amount (generally one share of common stock of the Company for each OP Unit/DownREIT Unit), as defined in the partnership agreement of the Operating Partnership or the DownREIT Partnership, as applicable. Accordingly, the Company records the OP Units/DownREIT Units outside of permanent equity and reports the OP Units/DownREIT Units at their redemption value using the Company’s stock price at each balance sheet date. The following table sets forth redeemable noncontrolling interests in the Operating Partnership and DownREIT Partnership for the following period ( dollars in thousands ​ ​ ​ ​ ​ Redeemable noncontrolling interests in the Operating Partnership and DownREIT Partnership, December 31, 2020 $ 856,294 ​ Mark-to-market adjustment to redeemable noncontrolling interests in the Operating Partnership and DownREIT Partnership ​ 131,700 ​ Conversion of OP Units/DownREIT Units to Common Stock ​ (4,497) ​ Net income/(loss) attributable to redeemable noncontrolling interests in the Operating Partnership and DownREIT Partnership ​ 154 ​ Distributions to redeemable noncontrolling interests in the Operating Partnership and DownREIT Partnership ​ (8,586) ​ Vesting of Long-Term Incentive Plan Units ​ ​ 14,578 ​ Allocation of other comprehensive income/(loss) ​ 43 ​ Redeemable noncontrolling interests in the Operating Partnership and DownREIT Partnership, March 31, 2021 ​ $ 989,686 ​ ​ Noncontrolling Interests Noncontrolling interests represent interests of unrelated partners and unvested LTIP Units in certain consolidated affiliates, and are presented as part of equity on the Consolidated Balance Sheets since these interests are not redeemable. Net (income)/loss attributable to noncontrolling interests The Company grants LTIP Units to certain employees and non-employee directors. The LTIP Units represent an ownership interest in the Operating Partnership and have vesting terms of between one Noncontrolling interests related to long-term incentive plan units represent the unvested LTIP Units of these employees and non-employee directors in the Operating Partnership. The net income/(loss) allocated to the unvested LTIP Units are included in Net (income)/loss attributable to noncontrolling interests

FAIR VALUE OF DERIVATIVES AND F

FAIR VALUE OF DERIVATIVES AND FINANCIAL INSTRUMENTS	3 Months Ended
	Mar. 31, 2021
FAIR VALUE OF DERIVATIVES AND FINANCIAL INSTRUMENTS
FAIR VALUE OF DERIVATIVES AND FINANCIAL INSTRUMENTS	10. FAIR VALUE OF DERIVATIVES AND FINANCIAL INSTRUMENTS Fair value is based on the price that would be received to sell an asset or the exit price that would be paid to transfer a liability in an orderly transaction between market participants at the measurement date. A three-level valuation hierarchy prioritizes observable and unobservable inputs used to measure fair value. The fair value hierarchy consists of three broad levels, which are described below: ● Level 1 — Quoted prices in active markets for identical assets or liabilities that the entity has the ability to access. ● Level 2 — Observable inputs other than prices included in Level 1, such as quoted prices for similar assets and liabilities in active markets; quoted prices for identical or similar assets and liabilities in markets that are not active; or other inputs that are observable or can be corroborated with observable market data. ● Level 3 — Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets and liabilities. This includes certain pricing models, discounted cash flow methodologies and similar techniques that use significant unobservable inputs. The estimated fair values of the Company’s financial instruments either recorded or disclosed on a recurring basis as of March 31, 2021 and December 31, 2020, are summarized as follows (dollars in thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value at March 31, 2021, Using ​ ​ Total ​ ​ ​ Quoted ​ ​ ​ ​ ​ ​ Carrying ​ ​ ​ Prices in ​ ​ ​ ​ ​ ​ Amount in ​ ​ ​ Active ​ ​ ​ ​ ​ ​ ​ Statement of ​ ​ ​ ​ Markets ​ Significant ​ ​ ​ ​ ​ Financial ​ Fair Value ​ for Identical ​ Other ​ Significant ​ ​ Position at ​ Estimate at ​ Assets or ​ Observable ​ Unobservable ​ ​ March 31, ​ March 31, ​ Liabilities ​ Inputs ​ Inputs ​ ​ 2021 (a) ​ 2021 ​ (Level 1) ​ (Level 2) ​ (Level 3) Description: ​ ​ ​ ​ ​ ​ Notes receivable, net (b) ​ $ 155,206 ​ $ 169,001 ​ $ — ​ $ — ​ $ 169,001 Derivatives - Interest rate contracts (c) ​ 9 ​ 9 ​ — ​ 9 ​ — Total assets ​ $ 155,215 ​ $ 169,010 ​ $ — ​ $ 9 ​ $ 169,001 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Derivatives - Interest rate contracts (c) ​ $ 67 ​ $ 67 ​ $ — ​ $ 67 ​ $ — Secured debt instruments - fixed rate: (d) ​ ​ ​ ​ ​ ​ Mortgage notes payable ​ ​ 894,967 ​ ​ 898,675 ​ ​ — ​ ​ — ​ ​ 898,675 Secured debt instruments - variable rate: (d) ​ ​ ​ ​ ​ ​ Tax-exempt secured notes payable ​ 27,000 ​ 27,000 ​ — ​ — ​ 27,000 Unsecured debt instruments: (d) ​ ​ ​ ​ ​ ​ Working capital credit facility ​ ​ 17,813 ​ ​ 17,813 ​ ​ — ​ ​ — ​ ​ 17,813 Commercial paper program ​ ​ 210,000 ​ ​ 210,000 ​ ​ — ​ ​ — ​ ​ 210,000 Unsecured notes ​ ​ 3,921,215 ​ ​ 3,983,183 ​ ​ — ​ ​ — ​ ​ 3,983,183 Total liabilities ​ $ 5,071,062 ​ $ 5,136,738 ​ $ — ​ $ 67 ​ $ 5,136,671 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Redeemable noncontrolling interests in the Operating Partnership and DownREIT Partnership (e) ​ $ 989,686 ​ $ 989,686 ​ $ — ​ $ 989,686 ​ $ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value at December 31, 2020, Using ​ ​ Total ​ ​ ​ Quoted ​ ​ ​ ​ ​ ​ Carrying ​ ​ ​ Prices in ​ ​ ​ ​ ​ ​ Amount in ​ ​ ​ Active ​ ​ ​ ​ ​ ​ Statement of ​ ​ ​ Markets ​ Significant ​ ​ ​ ​ Financial ​ Fair Value ​ for Identical ​ Other ​ Significant ​ ​ Position at ​ Estimate at ​ Assets or ​ Observable ​ Unobservable ​ ​ December 31, ​ December 31, ​ Liabilities ​ Inputs ​ Inputs ​ 2020 (a) ​ 2020 ​ (Level 1) ​ (Level 2) ​ (Level 3) Description: ​ ​ ​ ​ ​ ​ Notes receivable, net (b) ​ $ 157,992 ​ $ 170,411 ​ $ — ​ $ — ​ $ 170,411 Derivatives - Interest rate contracts (c) ​ 2 ​ 2 ​ — ​ 2 ​ — Total assets ​ $ 157,994 ​ $ 170,413 ​ $ — ​ $ 2 ​ $ 170,411 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Derivatives - Interest rate contracts (c) ​ $ 167 ​ $ 167 ​ $ — ​ $ 167 ​ $ — Secured debt instruments - fixed rate: (d) ​ ​ ​ ​ ​ ​ Mortgage notes payable ​ ​ 837,473 ​ ​ 854,084 ​ ​ — ​ ​ — ​ ​ 854,084 Secured debt instruments - variable rate: (d) ​ ​ ​ ​ ​ ​ Tax-exempt secured notes payable ​ 27,000 ​ 27,000 ​ — ​ — ​ 27,000 Unsecured debt instruments: (d) ​ ​ ​ ​ ​ ​ ​ Working capital credit facility ​ ​ 28,024 ​ ​ 28,024 ​ ​ — ​ ​ — ​ ​ 28,024 Commercial paper program ​ ​ 190,000 ​ ​ 190,000 ​ ​ — ​ ​ — ​ ​ 190,000 Unsecured notes ​ ​ 3,922,314 ​ ​ 4,283,045 ​ ​ — ​ ​ — ​ ​ 4,283,045 Total liabilities ​ $ 5,004,978 ​ $ 5,382,320 ​ $ — ​ $ 167 ​ $ 5,382,153 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Redeemable noncontrolling interests in the Operating Partnership and DownREIT Partnership (e) ​ $ 856,294 ​ $ 856,294 ​ $ — ​ $ 856,294 ​ $ — (a) Balances include fair market value adjustments and exclude deferred financing costs. (b) See Note 2, Significant Accounting Policies . (c) See Note 11, Derivatives and Hedging Activity . (d) See Note 7, Secured and Unsecured Debt, Net . (e) See Note 9, Noncontrolling Interests. There were no transfers into or out of any of the levels of the fair value hierarchy during the three months ended March 31, 2021. Financial Instruments Carried at Fair Value The fair values of interest rate swaps are determined using the market standard methodology of netting the discounted future fixed cash receipts (or payments) and the discounted expected variable cash payments (or receipts). The variable cash payments (or receipts) are based on an expectation of future interest rates (forward curves) derived from observable market interest rate curves. The fair values of interest rate swaps and caps are determined using the market standard methodology of discounting the future expected cash receipts that would occur if variable interest rates rise above the strike rate of the caps. The variable interest rates used in the calculation of projected receipts on the cap are based on an expectation of future interest rates derived from observable market interest rate curves and volatilities. The Company incorporates credit valuation adjustments to appropriately reflect both its own nonperformance risk and the respective counterparty’s nonperformance risk in the fair value measurements. In adjusting the fair value of its derivative contracts for the effect of nonperformance risk, the Company has considered the impact of netting and any applicable credit enhancements, such as collateral postings, thresholds, mutual puts, and guarantees. Although the Company has determined that the majority of the inputs used to value its derivatives fall within Level 2 of the fair value hierarchy, the credit valuation adjustments associated with its derivatives utilize Level 3 inputs, such as estimates of current credit spreads to evaluate the likelihood of default by itself and its counterparties. However, as of March 31, 2021 and December 31, 2020, the Company has assessed the significance of the impact of the credit valuation adjustments on the overall valuation of its derivative positions and has determined that the credit valuation adjustments are not significant to the overall valuation of its derivatives. As a result, the Company has determined that its derivative valuations in their entirety are classified in Level 2 of the fair value hierarchy. In conjunction with the FASB’s fair value measurement guidance, the Company made an accounting policy election to measure the credit risk of its derivative financial instruments that are subject to master netting agreements on a net basis by counterparty portfolio. Redeemable noncontrolling interests in the Operating Partnership and DownREIT Partnership have a redemption feature and are marked to their redemption value. The redemption value is based on the fair value of the Company’s common stock at the redemption date, and therefore, is calculated based on the fair value of the Company’s common stock at the balance sheet date. Since the valuation is based on observable inputs such as quoted prices for similar instruments in active markets, redeemable noncontrolling interests in the Operating Partnership and DownREIT Partnership are classified as Level 2. Financial Instruments Not Carried at Fair Value At March 31, 2021 and December 31, 2020, the fair values of cash and cash equivalents, restricted cash, accounts receivable, prepaids, real estate taxes payable, accrued interest payable, security deposits and prepaid rent, distributions payable and accounts payable approximated their carrying values because of the short term nature of these instruments. The estimated fair values of other financial instruments, which includes notes receivable and debt instruments, are classified in Level 3 of the fair value hierarchy due to the significant unobservable inputs that are utilized in their respective valuations.

DERIVATIVES AND HEDGING ACTIVIT

DERIVATIVES AND HEDGING ACTIVITY	3 Months Ended
	Mar. 31, 2021
DERIVATIVES AND HEDGING ACTIVITY
DERIVATIVES AND HEDGING ACTIVITY	11. DERIVATIVES AND HEDGING ACTIVITY Risk Management Objective of Using Derivatives The Company is exposed to certain risks arising from both its business operations and economic conditions. The Company principally manages its exposures to a wide variety of business and operational risks through management of its core business activities. The Company manages economic risks, including interest rate, liquidity, and credit risk, primarily by managing the amount, sources, and duration of its debt funding and through the use of derivative financial instruments. Specifically, the Company may enter into derivative financial instruments to manage exposures that arise from business activities that result in the receipt or payment of future known and uncertain cash amounts, the value of which are determined by interest rates. The Company’s derivative financial instruments are used to manage differences in the amount, timing, and duration of the Company’s known or expected cash receipts and its known or expected cash payments principally related to the Company’s investments and borrowings. Cash Flow Hedges of Interest Rate Risk The Company’s objectives in using interest rate derivatives are to add stability to interest expense and to manage its exposure to interest rate movements. To accomplish this objective, the Company primarily uses interest rate swaps and caps as part of its interest rate risk management strategy. Interest rate swaps designated as cash flow hedges involve the receipt of variable-rate amounts from a counterparty in exchange for the Company making fixed-rate payments over the life of the agreements without exchange of the underlying notional amount. Interest rate caps designated as cash flow hedges involve the receipt of variable-rate amounts from a counterparty if interest rates rise above the strike rate on the contract in exchange for an up-front premium. The changes in the fair value of derivatives designated and that qualify as cash flow hedges are recorded in Accumulated other comprehensive income/(loss), net Amounts reported in Accumulated other comprehensive income/(loss), net Interest expense As of March 31, 2021, the Company had the following outstanding interest rate derivatives that were designated as cash flow hedges of interest rate risk ( dollars in thousands ​ ​ ​ ​ ​ ​ ​ Number of ​ Product ​ Instruments ​ Notional Interest rate swaps and caps ​ 4 ​ $ 334,880 ​ Derivatives not designated as hedges are not speculative and are used to manage the Company’s exposure to interest rate movements and other identified risks but do not meet the strict hedge accounting requirements of GAAP. Changes in the fair value of derivatives not designated in hedging relationships are recorded directly in earnings. As of March 31, 2021, no derivatives not designated as hedges were held by the Company. Tabular Disclosure of Fair Values of Derivative Instruments on the Consolidated Balance Sheet The table below presents the fair value of the Company’s derivative financial instruments as well as their classification on the Consolidated Balance Sheets as of March 31, 2021 and December 31, 2020 ( dollars in thousands ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Asset Derivatives ​ Liability Derivatives ​ ​ (included in Other assets ) ​ (included in Other liabilities ) ​ ​ Fair Value at: ​ Fair Value at: ​ ​ March 31, ​ December 31, ​ March 31, ​ December 31, ​ ​ 2021 ​ 2020 ​ 2021 ​ 2020 Derivatives designated as hedging instruments: ​ ​ ​ ​ Interest rate products ​ $ 9 ​ $ 2 ​ $ 67 ​ $ 167 ​ Tabular Disclosure of the Effect of Derivative Instruments on the Consolidated Statements of Operations The tables below present the effect of the Company’s derivative financial instruments on the Consolidated Statements of Operations for the three months ended March 31, 2021 and 2020 ( dollars in thousands ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Gain/(Loss) Recognized in ​ ​ ​ ​ Gain/(Loss) Reclassified ​ Interest expense ​ ​ Unrealized holding gain/(loss) ​ from Accumulated OCI into ​ (Amount Excluded from ​ ​ Recognized in OCI ​ Interest expense ​ Effectiveness Testing) Derivatives in Cash Flow Hedging Relationships 2021 2020 2021 2020 2021 2020 Three Months Ended March 31, ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Interest rate products ​ $ 127 ​ $ (2,917) ​ $ (446) ​ $ (357) ​ $ — ​ $ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ ​ March 31, ​ ​ 2021 ​ 2020 Total amount of Interest expense ​ $ 78,156 ​ $ 39,317 ​ Credit-risk-related Contingent Features The Company has agreements with its derivative counterparties that contain a provision where the Company could be declared in default on its derivative obligations if repayment of the underlying indebtedness is accelerated by the lender due to the Company’s default on the indebtedness. The Company has certain agreements with some of its derivative counterparties that contain a provision where, in the event of default by the Company or the counterparty, the right of setoff may be exercised. Any amount payable to one party by the other party may be reduced by its setoff against any amounts payable by the other party. Events that give rise to default by either party may include, but are not limited to, the failure to pay or deliver payment under the derivative agreement, the failure to comply with or perform under the derivative agreement, bankruptcy, a merger without assumption of the derivative agreement, or in a merger, a surviving entity’s creditworthiness is materially weaker than the original party to the derivative agreement. Tabular Disclosure of Offsetting Derivatives The Company has elected not to offset derivative positions on the consolidated financial statements. The tables below present the effect on its financial position had the Company made the election to offset its derivative positions as of March 31, 2021 and December 31, 2020 (dollars in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Gross Net Amounts of Gross Amounts Not Offset ​ ​ ​ ​ ​ ​ ​ ​ Amounts ​ Assets ​ in the Consolidated ​ ​ ​ ​ ​ Gross ​ Offset in the ​ Presented in the ​ Balance Sheet ​ ​ ​ ​ ​ Amounts of ​ Consolidated ​ Consolidated ​ ​ ​ ​ Cash ​ ​ ​ ​ ​ Recognized ​ Balance ​ Balance Sheets ​ Financial ​ Collateral ​ ​ ​ Offsetting of Derivative Assets ​ Assets ​ Sheets ​ (a) ​ Instruments Received Net Amount March 31, 2021 ​ $ 9 ​ $ — ​ $ 9 ​ $ — ​ $ — ​ $ 9 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2020 ​ $ 2 ​ $ — ​ $ 2 ​ $ — ​ $ — ​ $ 2 (a) Amounts reconcile to the aggregate fair value of derivative assets in the “Tabular Disclosure of Fair Values of Derivative Instruments on the Consolidated Balance Sheets” located in this footnote. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Gross Net Amounts of Gross Amounts Not Offset ​ ​ ​ ​ ​ ​ ​ ​ Amounts ​ Liabilities ​ in the Consolidated ​ ​ ​ ​ ​ Gross ​ Offset in the ​ Presented in the ​ Balance Sheet ​ ​ ​ ​ ​ Amounts of ​ Consolidated ​ Consolidated ​ ​ ​ ​ Cash ​ ​ ​ ​ ​ Recognized ​ Balance ​ Balance Sheets ​ Financial ​ Collateral ​ ​ ​ Offsetting of Derivative Liabilities Liabilities Sheets (a) Instruments Posted Net Amount March 31, 2021 ​ $ 67 ​ $ — ​ $ 67 ​ $ — ​ $ — ​ $ 67 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2020 ​ $ 167 ​ $ — ​ $ 167 ​ $ — ​ $ — ​ $ 167 (a) Amounts reconcile to the aggregate fair value of derivative liabilities in the “Tabular Disclosure of Fair Values of Derivative Instruments on the Consolidated Balance Sheets” located in this footnote.

STOCK BASED COMPENSATION

STOCK BASED COMPENSATION	3 Months Ended
	Mar. 31, 2021
EMPLOYEE BENEFIT PLANS
STOCK BASED COMPENSATION	12. STOCK BASED COMPENSATION The Company recognized stock based compensation expense, inclusive of awards granted to our non-employee directors, net of capitalization, of $4.9 million and $6.8 million during the three months ended March 31, 2021 and 2020, respectively, which are included in General and Administrative

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	3 Months Ended
	Mar. 31, 2021
COMMITMENTS AND CONTINGENCIES
COMMITMENTS AND CONTINGENCIES	13. COMMITMENTS AND CONTINGENCIES Commitments Real Estate Commitments The following summarizes the Company’s real estate commitments at March 31, 2021 ( dollars in thousands ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Number ​ UDR's ​ UDR's Remaining ​ ​ ​ Properties ​ Investment (a) ​ Commitment ​ Wholly-owned — under development 5 ​ $ 243,200 ​ $ 258,300 Joint ventures: ​ ​ Preferred equity investments 2 ​ ​ 7,082 (b) ​ 43,104 (b) Real estate technology investments: ​ ​ ​ ​ ​ ​ ​ ​ ​ RETV I ​ - ​ ​ 22,641 ​ ​ 5,220 ​ RETV II ​ - ​ ​ 2,184 ​ ​ 14,025 ​ Total ​ $ 275,107 ​ $ 301,404 (a) Represents UDR’s investment as of March 31, 2021. (b) Represents UDR’s investment in and remaining commitment for Makers Rise and 121 at Watters, which are under development as of March 31, 2021. Purchase Commitments In April 2021, the Company entered into a contract to acquire a 945 apartment home operating community located in Frisco, Texas for a purchase price of approximately $167.0 million. The Company made a $7.5 million deposit on the purchase, which is generally non-refundable other than due to a failure of closing conditions pursuant to the terms of the purchase agreement. The acquisition is expected to close in 2021, subject to customary closing conditions. Contingencies Litigation and Legal Matters The Company is subject to various legal proceedings and claims arising in the ordinary course of business. The Company cannot determine the ultimate liability with respect to such legal proceedings and claims at this time. The Company believes that such liability, to the extent not provided for through insurance or otherwise, will not have a material adverse effect on our financial condition, results of operations or cash flows.

REPORTABLE SEGMENTS

REPORTABLE SEGMENTS	3 Months Ended
	Mar. 31, 2021
REPORTABLE SEGMENTS
REPORTABLE SEGMENTS	14. REPORTABLE SEGMENTS GAAP guidance requires that segment disclosures present the measure(s) used by the Chief Operating Decision Maker to decide how to allocate resources and for purposes of assessing such segments’ performance. UDR’s Chief Operating Decision Maker is comprised of several members of its executive management team who use several generally accepted industry financial measures to assess the performance of the business for our reportable operating segments. UDR owns and operates multifamily apartment communities that generate rental and other property related income through the leasing of apartment homes to a diverse base of tenants. The primary financial measures for UDR’s apartment communities are rental income and net operating income (“NOI”). Rental income represents gross market rent less adjustments for concessions, vacancy loss and bad debt. NOI is defined as rental income less direct property rental expenses. Rental expenses include real estate taxes, insurance, personnel, utilities, repairs and maintenance, administrative and marketing. Excluded from NOI is property management expense, which is calculated as 3.0% of property revenue, and land rent. Property management expense covers costs directly related to consolidated property operations, inclusive of corporate management, regional supervision, accounting and other costs. UDR’s Chief Operating Decision Maker utilizes NOI as the key measure of segment profit or loss. UDR’s two reportable segments are Same-Store Communities Non-Mature Communities/Other ● Same-Store Communities represent those communities acquired, developed, and stabilized prior to January 1, 2020 and held as of March 31, 2021. A comparison of operating results from the prior year is meaningful as these communities were owned and had stabilized occupancy and operating expenses as of the beginning of the prior period, there is no plan to conduct substantial redevelopment activities, and the community is not classified as held for disposition within the current year. A community is considered to have stabilized occupancy once it achieves 90% occupancy for at least three consecutive months. ● Non-Mature Communities/Other represent those communities that do not meet the criteria to be included in Same-Store Communities , including, but not limited to, recently acquired, developed and redeveloped communities, and the non-apartment components of mixed use properties. Management evaluates the performance of each of our apartment communities on a Same-Store Community Non-Mature Community/Other All revenues are from external customers and no single tenant or related group of tenants contributed 10% or more of UDR’s total revenues during the three months ended March 31, 2021 and 2020. ​ The following is a description of the principal streams from which the Company generates its revenue: Lease Revenue ​ Lease revenue related to leases is recognized on an accrual basis when due from residents or tenants in accordance with ASC 842, Leases ​ Lease revenue also includes all pass-through revenue from retail and residential leases and common area maintenance reimbursements from retail leases. These services represent non-lease components in a contract as the Company transfers a service to the lessee other than the right to use the underlying asset. The Company has elected the practical expedient under the leasing standard to not separate lease and non-lease components from its resident and retail lease contracts as the timing and pattern of revenue recognition for the non-lease component and related lease component are the same and the combined single lease component would be classified as an operating lease. ​ Other Revenue ​ Other revenue is generated by services provided by the Company to its retail and residential tenants and other unrelated third parties. Revenue is measured based on consideration specified in contracts with customers. The Company recognizes when it satisfies a performance obligation by providing the services specified in a contract to the customer. ​ Joint venture management and other fees ​ The Joint venture management and other fees Joint venture management and other fees ​ The following table details rental income and NOI for UDR’s reportable segments for the three months ended March 31, 2021 and 2020, and reconciles NOI to Net income/(loss) attributable to UDR, Inc. (dollars in thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ ​ March 31, (a) ​ 2021 2020 Reportable apartment home segment lease revenue ​ ​ ​ ​ ​ ​ Same-Store Communities (a) ​ ​ ​ West Region ​ $ 100,170 ​ $ 111,215 Mid-Atlantic Region ​ 59,917 ​ 62,537 Northeast Region ​ 52,050 ​ 57,495 Southeast Region ​ 34,637 ​ 33,781 Southwest Region ​ 23,211 ​ 23,815 Non-Mature Communities/Other ​ 21,460 ​ 22,779 Total segment and consolidated lease revenue ​ $ 291,445 ​ $ 311,622 ​ ​ ​ ​ ​ ​ ​ Reportable apartment home segment other revenue ​ ​ ​ ​ ​ ​ Same-Store Communities (a) ​ ​ ​ West Region ​ $ 2,718 ​ $ 2,930 Mid-Atlantic Region ​ 1,702 ​ 1,701 Northeast Region ​ 1,047 ​ 1,064 Southeast Region ​ 1,493 ​ 1,524 Southwest Region ​ 875 ​ 820 Non-Mature Communities/Other ​ 546 ​ 432 Total segment and consolidated other revenue ​ $ 8,381 ​ $ 8,471 ​ ​ ​ ​ ​ ​ ​ Total reportable apartment home segment rental income ​ ​ ​ ​ ​ ​ Same-Store Communities (a) ​ ​ ​ West Region ​ $ 102,888 ​ $ 114,145 Mid-Atlantic Region ​ 61,619 ​ 64,238 Northeast Region ​ 53,097 ​ 58,559 Southeast Region ​ 36,130 ​ 35,305 Southwest Region ​ 24,086 ​ 24,635 Non-Mature Communities/Other ​ 22,006 ​ 23,211 Total segment and consolidated rental income ​ $ 299,826 ​ $ 320,093 ​ ​ ​ ​ ​ ​ ​ Reportable apartment home segment NOI ​ ​ Same-Store Communities (a) ​ ​ West Region ​ $ 74,845 ​ $ 86,091 Mid-Atlantic Region ​ 42,402 ​ 45,317 Northeast Region ​ 33,343 ​ 40,323 Southeast Region ​ 24,317 ​ 24,537 Southwest Region ​ 14,834 ​ 15,383 Non-Mature Communities/Other ​ 11,317 ​ 13,814 Total segment and consolidated NOI ​ 201,058 ​ 225,465 Reconciling items: ​ ​ Joint venture management and other fees ​ 1,615 ​ 1,388 Property management ​ (8,995) ​ (9,203) Other operating expenses ​ (4,435) ​ (4,966) Real estate depreciation and amortization ​ (144,088) ​ (155,476) General and administrative ​ (12,736) ​ (14,978) Casualty-related (charges)/recoveries, net ​ (5,577) ​ (1,251) Other depreciation and amortization ​ (2,601) ​ (2,025) Gain/(loss) on sale of real estate owned ​ ​ 50,829 ​ ​ — Income/(loss) from unconsolidated entities ​ 4,922 ​ 3,367 Interest expense ​ (78,156) ​ (39,317) Interest income and other income/(expense), net ​ 2,057 ​ 2,700 Tax (provision)/benefit, net ​ (619) ​ (164) Net (income)/loss attributable to redeemable noncontrolling interests in the Operating Partnership and DownREIT Partnership ​ (154) ​ (313) Net (income)/loss attributable to noncontrolling interests ​ (16) ​ (6) Net income/(loss) attributable to UDR, Inc. ​ $ 3,104 ​ $ 5,221 (a) Same-Store Community population consisted of 45,403 apartment homes. ​ The following table details the assets of UDR’s reportable segments as of March 31, 2021 and December 31, 2020 (dollars in thousands) ​ ​ ​ ​ ​ ​ ​ ​ March 31, December 31, ​ ​ 2021 ​ 2020 Reportable apartment home segment assets: ​ ​ Same-Store Communities (a): ​ ​ West Region ​ $ 4,255,427 ​ $ 4,247,900 Mid-Atlantic Region ​ 2,703,939 ​ 2,698,049 Northeast Region ​ 2,904,450 ​ 2,900,017 Southeast Region ​ 978,568 ​ 974,754 Southwest Region ​ 896,728 ​ 897,505 Non-Mature Communities/Other ​ 1,356,788 ​ 1,353,247 Total segment assets ​ 13,095,900 ​ 13,071,472 Accumulated depreciation ​ (4,730,021) ​ (4,605,366) Total segment assets — net book value ​ 8,365,879 ​ 8,466,106 Reconciling items: ​ ​ Cash and cash equivalents ​ 1,172 ​ 1,409 Restricted cash ​ 33,428 ​ 22,762 Notes receivable, net ​ 155,206 ​ 157,992 Investment in and advances to unconsolidated joint ventures, net ​ 620,111 ​ 600,233 Operating lease right-of-use assets ​ ​ 200,064 ​ ​ 200,913 Other assets ​ 190,696 ​ 188,118 Total consolidated assets ​ $ 9,566,556 ​ $ 9,637,533 (a) Same-Store Community population consisted of 45,403 apartment homes. ​ Markets included in the above geographic segments are as follows: i. West Region — Orange County, San Francisco, Seattle, Monterey Peninsula, Los Angeles, Other Southern California and Portland ii. Mid-Atlantic Region — Metropolitan D.C., Baltimore and Richmond iii. Northeast Region — Boston, New York and Philadelphia iv. Southeast Region — Tampa, Orlando, Nashville and Other Florida v. Southwest Region — Dallas, Austin and Denver

SIGNIFICANT ACCOUNTING POLICI_2

SIGNIFICANT ACCOUNTING POLICIES (Policies)	3 Months Ended
	Mar. 31, 2021
SIGNIFICANT ACCOUNTING POLICIES
Recent Accounting Pronouncements	Recent Accounting Pronouncements In March 2020, the SEC adopted rules that amended the financial disclosure requirements for subsidiary issuers and guarantors of registered debt securities in Rule 3-10 of Regulation S-X. Subsequently, in November 2020, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2020-09, Debt (Topic 470): Amendments to SEC Paragraphs Pursuant to SEC Release No. 33-10762, which revises SEC paragraphs of the codification to reflect, as appropriate, the amended disclosure requirements mentioned above. Under the amended rules, parent companies can provide alternative disclosures in lieu of separate audited financial statements of subsidiary issuers and guarantors that meet certain criteria. We evaluated the criteria and determined that we are eligible for the exceptions, which allow us to provide alternative disclosures for the Operating Partnership, which guarantees certain outstanding debt securities issued by the Company. Both rules became effective for the Company on January 4, 2021, and we adopted these amendments for the three months ended March 31, 2021. As a result of the amendments, the Operating Partnership, as subsidiary guarantor, is no longer subject to the filing requirements under Section 15(d) of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), and will no longer file separate periodic and current reports in reliance on Rule 12h-5 under the Exchange Act. The alternative disclosures related to the Operating Partnership are presented in Item 2 "Management's Discussion and Analysis of Financial Condition and Results of Operations” in this report. ​ I n August 2020, the FASB issued ASU 2020-06, Debt—Debt With Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging—Contracts in E ntity’s Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity ​ In March 2020, the FASB issued ASU 2020-04, Reference Rate Reform (Topic 848)
Principles of Consolidation	Principles of Consolidation The Company accounts for subsidiary partnerships, joint ventures and other similar entities in which it holds an ownership interest in accordance with the consolidation guidance. The Company first evaluates whether each entity is a variable interest entity (“VIE”). Under the VIE model, the Company consolidates an entity when it has control to direct the activities of the VIE and the obligation to absorb losses or the right to receive benefits that could potentially be significant to the VIE. Under the voting model, the Company consolidates an entity when it controls the entity through ownership of a majority voting interest.
Real Estate Sales Gain Recognition	Real Estate Sales Gain Recognition ​ For sale transactions resulting in a transfer of a controlling financial interest of a property, the Company generally derecognizes the related assets and liabilities from its Consolidated Balance Sheets and records the gain or loss in the period in which the transfer of control occurs. If control of the property has not transferred to the counterparty, the criteria for derecognition are not met and the Company will continue to recognize the related assets and liabilities on its Consolidated Balance Sheets. ​ Sale transactions to entities in which the Company sells a controlling financial interest in a property but retains a noncontrolling interest are accounted for as partial sales. Partial sales resulting in a change in control are accounted for at fair value and a full gain or loss is recognized. Therefore, the Company will record a gain or loss on the partial interest sold, and the initial measurement of our retained interest will be accounted for at fair value. ​ Sales of real estate to joint ventures or other noncontrolled investees are also accounted for at fair value and the Company will record a full gain or loss in the period the property is contributed. ​ To the extent that the Company acquires a controlling financial interest in a property that it previously accounted for as an equity method investment, the Company will not remeasure its previously held interest if the acquisition is treated as an asset acquisition. The Company will include the carrying amount of its previously held equity method interest along with the consideration paid and transaction costs incurred in determining the amounts to allocate to the related assets and liabilities acquired on its Consolidated Balance Sheets. When treated as an asset acquisition, the Company will not recognize a gain or loss on consolidation of a property.
Allowance for Credit Losses	Allowance for Credit Losses The Company accounts for allowance for credit losses under the current expected credit loss (“CECL”) impairment model for its financial assets, including trade and other receivables, held-to-maturity debt securities, loans and other financial instruments, and presents the net amount of the financial instrument expected to be collected. The CECL impairment model excludes operating lease receivables. The CECL impairment model requires an estimate of expected credit losses, measured over the contractual life of an instrument, that considers forecasts of future economic conditions in addition to information about past events and current conditions. Based on this model, we analyze the following criteria, as applicable in developing allowances for credit losses: historical loss information, the borrower’s ability to make scheduled payments, the remaining time to maturity, the value of underlying collateral, projected future performance of the borrower and macroeconomic trends. ​ The Company measures credit losses of financial assets on a collective (pool) basis when similar risk characteristics exist. If the Company determines that a financial asset does not share risk characteristics with its other financial assets, the Company evaluates the financial asset for expected credit losses on an individual basis. Allowance for credit losses are recorded as a direct reduction from an asset’s amortized cost basis. Credit losses and recoveries are recorded in Interest income and other income/(expense), net ​ The Company has made the optional election provided by the standard not to measure allowance for credit losses for accrued interest receivables as the Company writes off any uncollectible accrued interest receivables in a timely manner. The Company periodically evaluates the collectability of its accrued interest receivables. A write-off is recorded when the Company concludes that all or a portion of its accrued interest receivable balance is no longer collectible.
Notes Receivable	Notes Receivable Notes receivable relate to financing arrangements which are typically secured by real estate, real estate related projects or other assets. Certain of the loans we extend may include characteristics such as options to purchase the project within a specific time window following expected project completion. These characteristics can cause the loans to fall under the definition of a VIE, and thus trigger consolidation consideration. We consider the facts and circumstances pertinent to each loan, including the relative amount of financing we are contributing to the overall project cost, decision making rights or control we hold, and our rights to expected residual gains or our obligations to absorb expected residual losses from the project. If we are deemed to be the primary beneficiary of a VIE due to holding a controlling financial interest, the majority of decision making control, or by other means, consolidation of the VIE would be required. The Company has concluded that it is not the primary beneficiary of the borrowing entities. Additionally, we analyze each loan arrangement that involves real estate development to consider whether the loan qualifies for accounting as a loan or as an investment in a real estate development project. The Company has evaluated its real estate loans, where appropriate, for accounting treatment as loans versus real estate development projects, as required by ASC 310-10. For each loan, the Company has concluded that the characteristics and the facts and circumstances indicate that loan accounting treatment is appropriate. The following table summarizes our Notes receivable, net dollars in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Interest rate at ​ Balance Outstanding ​ March 31, March 31, December 31, ​ ​ 2021 ​ 2021 ​ 2020 Note due February 2021 (a) ​ N/A ​ $ — ​ $ 4,000 Note due May 2022 (b) ​ 8.00 % ​ 20,000 ​ ​ 20,000 Note due October 2022 (c) 4.75 % ​ 115,000 ​ ​ 115,000 Note due January 2023 (d) ​ 10.00 % ​ 20,885 ​ ​ 19,685 Notes Receivable ​ ​ ​ ​ 155,885 ​ ​ 158,685 Allowance for credit losses ​ ​ ​ ​ (679) ​ ​ (693) Total notes receivable, net ​ $ 155,206 ​ $ 157,992 (a) In May 2020, the Company entered into a promissory note with an unaffiliated third party with an aggregate commitment of $4.0 million, in connection with the sale of an operating community. In January 2021, the unaffiliated third party repaid the $4.0 million promissory note. (b) The Company has a secured note with an unaffiliated third party with an aggregate commitment of $20.0 million, all of which has been funded. The note is secured by a parcel of land and related land improvements. In September 2020, the developer defaulted on the loan. As a result of the default, in April 2021, UDR took title to the property pursuant to a deed in lieu of foreclosure. At that time, the Company reclassified the related balance as Real estate owned (c) The Company has a secured note with an unaffiliated third party with an aggregate commitment of $115.0 million, all of which has been funded. Interest payments are due when the loan matures. The note is secured by a first priority deed of trust on a 259 apartment home operating community in Bellevue, Washington, which was completed in 2020. When the note was funded, the Company also entered into a purchase option agreement and paid a deposit of $10.0 million, which gave the Company the option to acquire the community at a fixed price of $170.0 million. In August 2020, the Company exercised the purchase option. The purchase is expected to close in 2021. The deposit is generally nonrefundable other than due to a failure of closing conditions pursuant to the terms of the agreement. If the Company fails to close the purchase other than due to seller’s failure or other breaches in the purchase option agreement, per the terms of the agreement, the note will be modified to extend the maturity date to 10 years following the date the temporary certificate of occupancy was issued, which was July 2020. Upon modification, the loan would be interest only for the first three years and after such date payments will be based on a 30-year amortization schedule . (d) The Company has a secured note with an unaffiliated third party with an aggregate commitment of $22.0 million, of which $20.9 million has been funded, including $1.2 million funded during the three months ended March 31, 2021. Interest payments are due monthly. The note matures at the earliest of the following: (a) the closing of any private or public capital raising in the amount of $5.0 million or greater; (b) an acquisition; (c) acceleration in the event of default; or (d) January 2023. In January 2021, the terms of this secured note were amended to increase the aggregate commitment from $20.0 million to $22.0 million. Interest payments are due monthly and the maturity date of the note remains in January 2023. The Company recognized $1.9 million and $2.6 million of interest income for the notes receivable described above during the three months ended March 31, 2021 and 2020, respectively, none of which was related party interest. Interest income is included in Interest income and other income/(expense), net
Comprehensive Income/(Loss)	Comprehensive Income/(Loss) Comprehensive income/(loss), which is defined as the change in equity during each period from transactions and other events and circumstances from nonowner sources, including all changes in equity during a period except for those resulting from investments by or distributions to stockholders, is displayed in the accompanying Consolidated Statements of Comprehensive Income/(Loss). For the three months ended March 31, 2021 and 2020, the Company’s other comprehensive income/(loss) consisted of the gain/(loss) on derivative instruments that are designated as and qualify as cash flow hedges, (gain)/loss on derivative instruments reclassified from other comprehensive income/(loss) into earnings, and the allocation of other comprehensive income/(loss) to noncontrolling interests. The (gain)/loss on derivative instruments reclassified from other comprehensive income/(loss) is included in Interest expense Derivatives and Hedging Activity,
Income Taxes	Income Taxes Due to the structure of the Company as a REIT and the nature of the operations for the operating properties, no provision for federal income taxes has been provided for at UDR. Historically, the Company has generally incurred only state and local excise and franchise taxes. UDR has elected for certain consolidated subsidiaries to be treated as taxable REIT subsidiaries (“TRS”). Income taxes for our TRS are accounted for under the asset and liability method. Deferred tax assets and liabilities are recognized for future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax basis. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities from a change in tax rate is recognized in earnings in the period of the enactment date. The Company’s deferred tax assets/(liabilities) are generally the result of differing depreciable lives on capitalized assets, temporary differences between book and tax basis of assets and liabilities and timing of expense recognition for certain accrued liabilities. As of March 31, 2021 and December 31, 2020, UDR’s net deferred tax asset/(liability) was ($0.6) million and ($3.2) million, respectively, and are recorded in Accounts payable, accrued expenses and other liabilities GAAP defines a recognition threshold and measurement attribute for the financial statement recognition and measurement of a tax position taken or expected to be taken in a tax return. GAAP also provides guidance on derecognition, classification, interest and penalties, accounting for interim periods, disclosure and transition. The Company recognizes its tax positions and evaluates them using a two-step process. First, UDR determines whether a tax position is more likely than not (greater than 50 percent probability) to be sustained upon examination, including resolution of any related appeals or litigation processes, based on the technical merits of the position. Second, the Company will determine the amount of benefit to recognize and record the amount that is more likely than not to be realized upon ultimate settlement. The Company invests in assets that qualify for federal investment tax credits (“ITC”) through our TRS. An ITC reduces federal income taxes payable when qualifying depreciable property is acquired. The ITC is determined as a percentage of cost of the assets. The Company accounts for ITCs under the deferral method, under which the tax benefit from the ITC is deferred and amortized as a tax benefit into Tax (provision)/benefit, net Accounts payable, accrued expenses and other liabilities UDR had no material unrecognized tax benefit, accrued interest or penalties at March 31, 2021. UDR and its subsidiaries are subject to federal income tax as well as income tax of various state and local jurisdictions. The tax years 2017 through 2019 remain open to examination by tax jurisdictions to which we are subject. When applicable, UDR recognizes interest and/or penalties related to uncertain tax positions in Tax (provision)/benefit, net
Forward Sales Agreements	Forward Sales Agreements ​ The Company utilizes forward sales agreements for the future issuance of its common stock. When the Company enters into a forward sales agreement, the contract requires the Company to sell its shares to a counterparty at a predetermined price at a future date. The net sales price and proceeds attained by the Company will be determined on the dates of settlement, with adjustments during the term of the contract for the Company’s anticipated dividends as well as for a daily interest factor that varies with changes in the federal funds rate. The Company generally has the ability to determine the dates and method of settlement (i.e., gross physical settlement, net share settlement or cash settlement), subject to certain conditions and the right of the counterparty to accelerate settlement under certain circumstances. ​ The Company accounts for the shares of common stock reserved for issuance upon settlement as equity in accordance with ASC 815-40, Contracts in Entity's Own Equity ​ The guidance establishes a two-step process for evaluating whether an equity-linked financial instrument is considered indexed to its own stock, first, evaluating the instrument’s contingent exercise provisions and second, evaluating the instrument’s settlement provisions. When entering into forward sales agreements, we determined that (i) none of the agreement’s exercise contingencies are based on observable markets or indices besides those related to the market for our own stock price; and (ii) none of the settlement provisions preclude the agreements from being indexed to our own stock. ​ Before the issuance of shares of common stock, upon physical or net share settlement of the forward sales agreements, the Company expects that the shares issuable upon settlement of the forward sales agreements will be reflected in its diluted income/(loss) per share calculations using the treasury stock method. Under this method, the number of shares of common stock used in calculating diluted income/(loss) per share is deemed to be increased by the excess, if any, of the number of shares of common stock that would be issued upon full physical settlement of the forward sales agreements over the number of shares of common stock that could be purchased by the Company in the open market (based on the average market price during the period) using the proceeds receivable upon full physical settlement (based on the adjusted forward sale price at the end of the reporting period). When the Company physically or net share settles any forward sales agreement, the delivery of shares of common stock would result in an increase in the number of weighted average common shares outstanding and dilution to basic income/(loss) per share. (See Note 8, Income/(Loss) per Share
Impact of COVID-19 Pandemic	Impact of COVID-19 Pandemic ​ The Company continues to closely monitor the impact of the COVID-19 pandemic on all aspects of its business. The extent of the pandemic’s effect on our operational and financial performance will depend on future developments, including the duration and intensity of the pandemic, the timing and effectiveness of COVID-19 vaccines, the duration of government measures to mitigate the pandemic and the success of government rental assistance programs, all of which continue to be uncertain and difficult to predict. ​ Given the uncertainty, we cannot predict the effect on future periods, but the adverse impact that could occur on the Company’s future financial condition, results of operations and cash flows could be material ​ During the three months ended March 31, 2021, the Company performed an analysis in accordance with the ASC 842, Leases, guidance to assess the collectibility of its operating lease receivables in light of the COVID-19 pandemic. This analysis included an assessment of collectibility of current and future rents and whether those lease payments were no longer probable of collection. In accordance with the leases guidance, if lease payments are no longer deemed to be probable over the life of the lease contract, we recognize revenue only when cash is received, and all existing contractual operating lease receivables and straight-line lease receivables are reserved. ​ As a result of its analysis, the Company reserved approximately $4.7 million of multifamily tenant lease receivables and approximately $0.8 million of retail tenant lease receivables for its wholly-owned communities and communities held by joint ventures for the three months ended March 31, 2021. In aggregate, the reserve is reflected as a $5.1 million reduction to Rental income and a $0.4 million reduction to Income/(loss) from unconsolidated entities on the Consolidated Statements of Operations for the three months ended March 31, 2021. The impact to deferred leasing commissions was not material for the three months ended March 31, 2021. ​ The Company did not recognize any other adjustments to the carrying amounts of assets or asset impairment charges due to the COVID-19 pandemic for the three months ended March 31, 2021.

SIGNIFICANT ACCOUNTING POLICI_3

SIGNIFICANT ACCOUNTING POLICIES (Tables)	3 Months Ended
	Mar. 31, 2021
SIGNIFICANT ACCOUNTING POLICIES
Summary of notes receivable, net	The following table summarizes our Notes receivable, net dollars in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Interest rate at ​ Balance Outstanding ​ March 31, March 31, December 31, ​ ​ 2021 ​ 2021 ​ 2020 Note due February 2021 (a) ​ N/A ​ $ — ​ $ 4,000 Note due May 2022 (b) ​ 8.00 % ​ 20,000 ​ ​ 20,000 Note due October 2022 (c) 4.75 % ​ 115,000 ​ ​ 115,000 Note due January 2023 (d) ​ 10.00 % ​ 20,885 ​ ​ 19,685 Notes Receivable ​ ​ ​ ​ 155,885 ​ ​ 158,685 Allowance for credit losses ​ ​ ​ ​ (679) ​ ​ (693) Total notes receivable, net ​ $ 155,206 ​ $ 157,992 (a) In May 2020, the Company entered into a promissory note with an unaffiliated third party with an aggregate commitment of $4.0 million, in connection with the sale of an operating community. In January 2021, the unaffiliated third party repaid the $4.0 million promissory note. (b) The Company has a secured note with an unaffiliated third party with an aggregate commitment of $20.0 million, all of which has been funded. The note is secured by a parcel of land and related land improvements. In September 2020, the developer defaulted on the loan. As a result of the default, in April 2021, UDR took title to the property pursuant to a deed in lieu of foreclosure. At that time, the Company reclassified the related balance as Real estate owned (c) The Company has a secured note with an unaffiliated third party with an aggregate commitment of $115.0 million, all of which has been funded. Interest payments are due when the loan matures. The note is secured by a first priority deed of trust on a 259 apartment home operating community in Bellevue, Washington, which was completed in 2020. When the note was funded, the Company also entered into a purchase option agreement and paid a deposit of $10.0 million, which gave the Company the option to acquire the community at a fixed price of $170.0 million. In August 2020, the Company exercised the purchase option. The purchase is expected to close in 2021. The deposit is generally nonrefundable other than due to a failure of closing conditions pursuant to the terms of the agreement. If the Company fails to close the purchase other than due to seller’s failure or other breaches in the purchase option agreement, per the terms of the agreement, the note will be modified to extend the maturity date to 10 years following the date the temporary certificate of occupancy was issued, which was July 2020. Upon modification, the loan would be interest only for the first three years and after such date payments will be based on a 30-year amortization schedule . (d) The Company has a secured note with an unaffiliated third party with an aggregate commitment of $22.0 million, of which $20.9 million has been funded, including $1.2 million funded during the three months ended March 31, 2021. Interest payments are due monthly. The note matures at the earliest of the following: (a) the closing of any private or public capital raising in the amount of $5.0 million or greater; (b) an acquisition; (c) acceleration in the event of default; or (d) January 2023. In January 2021, the terms of this secured note were amended to increase the aggregate commitment from $20.0 million to $22.0 million. Interest payments are due monthly and the maturity date of the note remains in January 2023.

REAL ESTATE OWNED (Tables)

REAL ESTATE OWNED (Tables)	3 Months Ended
	Mar. 31, 2021
REAL ESTATE OWNED
Summary of carrying amounts for real estate owned (at cost)	​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, December 31, ​ ​ 2021 ​ 2020 Land ​ $ 2,148,977 ​ $ 2,139,765 Depreciable property — held and used: ​ ​ Land improvements ​ 235,002 ​ 233,823 Building, improvements, and furniture, fixtures and equipment ​ 10,428,151 ​ 10,292,782 Real estate intangible assets ​ ​ 40,570 ​ ​ 40,570 Under development: ​ ​ Land and land improvements ​ 74,399 ​ 73,702 Building, improvements, and furniture, fixtures and equipment ​ 168,801 ​ 174,175 Real estate held for disposition: ​ ​ Land and land improvements ​ — ​ 15,184 Building, improvements, and furniture, fixtures and equipment ​ — ​ 101,471 Real estate owned ​ 13,095,900 ​ 13,071,472 Accumulated depreciation (a) ​ (4,730,021) ​ (4,605,366) Real estate owned, net ​ $ 8,365,879 ​ $ 8,466,106 (a) Accumulated depreciation is inclusive of $6.5 million of accumulated amortization related to real estate intangible assets. ​

JOINT VENTURES AND PARTNERSHI_2

JOINT VENTURES AND PARTNERSHIPS (Tables)	3 Months Ended
	Mar. 31, 2021
JOINT VENTURES AND PARTNERSHIPS
Schedule of unconsolidated joint ventures and partnerships	The following table summarizes the Company’s investment in and advances to unconsolidated joint ventures and partnerships, net, which are accounted for under the equity method of accounting as of March 31, 2021 and December 31, 2020 (dollars in thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Number of ​ Number of ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Operating ​ Apartment ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Income/(loss) from investments ​ ​ ​ ​ Communities ​ Homes ​ Investment at ​ UDR’s Ownership Interest ​ ​ Three Months Ended ​ Location of March 31, March 31, March 31, December 31, ​ March 31, ​ December 31, ​ March 31, Joint Ventures Properties 2021 2021 2021 2020 ​ 2021 ​ 2020 ​ 2021 2020 Operating: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ UDR/MetLife I ​ Los Angeles, CA ​ 1 ​ 150 ​ $ 26,001 ​ $ 26,426 ​ 50.0 % ​ 50.0 % ​ $ (475) ​ $ (454) UDR/MetLife II Various 7 1,250 ​ 186,312 ​ 151,353 ​ 50.0 % ​ 50.0 % ​ ​ (2,684) ​ ​ (91) Other UDR/MetLife Joint Ventures (a) Various 5 1,437 ​ 78,155 ​ 82,072 ​ 50.6 % ​ 50.6 % ​ ​ (3,382) ​ ​ (1,811) West Coast Development Joint Ventures (b) ​ Los Angeles, CA ​ — ​ — ​ ​ 311 ​ ​ 30,080 ​ 47.0 % ​ 47.0 % ​ ​ 2,486 ​ ​ (77) Investment in and advances to unconsolidated joint ventures, net, before preferred equity investments and real estate technology investments ​ $ 290,779 ​ $ 289,931 ​ ​ ​ ​ $ (4,055) ​ $ (2,433) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Investment at ​ Three Months Ended Developer Capital Program ​ ​ Years To ​ UDR March 31, December 31, March 31, and Real Estate Technology Investments (c) Location Rate Maturity ​ Commitment (d) 2021 2020 2021 2020 Preferred equity investments: ​ ​ ​ ​ ​ ​ ​ ​ ​ 1532 Harrison ​ San Francisco, CA ​ 11.0 % 1.2 ​ $ 24,645 ​ $ 35,069 ​ $ 34,135 ​ $ 929 ​ $ 836 1200 Broadway (e) (f) ​ Nashville, TN ​ 8.0 % 1.5 ​ ​ 55,558 ​ ​ 70,709 ​ ​ 69,330 ​ ​ 1,372 ​ ​ 1,281 Junction ​ Santa Monica, CA ​ 12.0 % 1.3 ​ ​ 8,800 ​ ​ 12,049 ​ ​ 11,699 ​ ​ 350 ​ ​ 314 1300 Fairmount (f) ​ Philadelphia, PA ​ 8.5 % 2.4 ​ ​ 51,393 ​ ​ 60,799 ​ ​ 59,544 ​ ​ 1,255 ​ ​ 1,166 Essex ​ Orlando, FL ​ 12.5 % 2.4 ​ ​ 12,886 ​ ​ 17,292 ​ ​ 16,770 ​ ​ 522 ​ ​ 466 Modera Lake Merritt (f) ​ Oakland, CA ​ 9.0 % 3.0 ​ ​ 27,250 ​ ​ 31,619 ​ ​ 30,928 ​ ​ 691 ​ ​ 574 Thousand Oaks (f) ​ Thousand Oaks, CA ​ 9.0 % 3.8 ​ ​ 20,059 ​ ​ 21,278 ​ ​ 17,919 ​ ​ 438 ​ ​ 24 Vernon Boulevard (f) ​ Queens, NY ​ 13.0 % 4.3 ​ ​ 40,000 ​ ​ 43,737 ​ ​ 42,360 ​ ​ 1,372 ​ ​ — Makers Rise (f) (g) ​ Herndon, VA ​ 9.0 % 4.7 ​ ​ 30,208 ​ ​ 7,070 ​ ​ — ​ ​ 96 ​ ​ — 121 at Watters (f) (h) ​ Allen, TX ​ 9.0 % 5.0 ​ ​ 19,846 ​ ​ 12 ​ ​ — ​ ​ 2 ​ ​ — Real estate technology investments: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ RETV I ​ N/A ​ N/A ​ N/A ​ ​ 18,000 ​ ​ 22,641 ​ ​ 20,587 ​ ​ 2,051 ​ ​ (150) RETV II ​ N/A ​ N/A ​ N/A ​ $ 16,500 ​ ​ 2,184 ​ ​ 2,283 ​ ​ (101) ​ ​ — Total Preferred Equity Investments and Real Estate Technology Investments ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 324,459 ​ ​ 305,555 ​ ​ 8,977 ​ ​ 4,511 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Sold joint ventures and other investments in prior year ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ — ​ ​ — ​ ​ — ​ ​ 1,289 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total Joint Ventures and Developer Capital Program and Real Estate Technology Investments, net (a) ​ ​ ​ ​ $ 615,238 ​ $ 595,486 ​ $ 4,922 $ 3,367 (a) As of March 31, 2021 and December 31, 2020, the Company’s negative investment in 13 th and Market Properties LLC of $4.9 million and $4.7 million, respectively, is included in Other UDR/MetLife Joint Ventures in the table above and recorded in Accounts payable, accrued expenses, and other liabilities on the Consolidated Balance Sheet. (b) In J anuary 2021, the joint venture sold its remaining community, a 293 home operating community located in Los Angeles, California, for a sales price of approximately $121.0 million. As a result, the Company recorded a gain on the sale of approximately $2.5 million . (c) The Developer Capital Program is the program through which the Company makes investments, including preferred equity investments, mezzanine loans or other structured investments that may receive a fixed yield on the investment and may include provisions pursuant to which the Company participates in the increase in value of the property upon monetization of the applicable property and/or holds fixed price purchase options. (d) Represents UDR’s maximum funding commitment only and therefore excludes other activity such as income from investments. (e) In April 2021, the balance was paid down by $12.5 million and the Company’s preferred return increased to 12.25%. The Company's preferred return will revert to 8.0% in February 2022 if no capital events occur prior to that date. (f) The Company’s preferred equity investment receives a variable percentage of the value created from the project upon a capital or liquidating event. (g) In January 2021, the Company entered into a joint venture agreement with an unaffiliated joint venture partner to develop and operate a 356 apartment home community in Herndon, Virginia. The Company’s preferred equity investment of $30.2 million earns a preferred return of 9.0% per annum and receives a variable percentage of the value created from the project upon a capital or liquidating event. The unaffiliated joint venture partner is the managing member of the joint venture and the developer of the community. The Company has concluded that it does not control the joint venture and accounts for it under the equity method of accounting . (h) In March 2021, the Company entered into a joint venture agreement with an unaffiliated joint venture partner to develop and operate a 469 apartment home community in Allen, Texas. The Company’s preferred equity investment of $19.8 million earns a preferred return of 9.0% per annum and receives a variable percentage of the value created from the project upon a capital or liquidating event. The unaffiliated joint venture partner is the managing member of the joint venture and the developer of the community. The Company has concluded that it does not control the joint venture and accounts for it under the equity method of accounting .
Combined summary of balance sheets relating to unconsolidated joint ventures and partnerships	Combined summary balance sheets relating to the unconsolidated joint ventures’ and partnerships’ (not just our proportionate share) are presented below as of March 31, 2021 and December 31, 2020 ( dollars in thousands ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, ​ December 31, ​ 2021 2020 Total real estate, net $ 2,111,478 $ 1,904,805 Real estate assets held for sale ​ — ​ 88,458 Cash and cash equivalents ​ 28,120 ​ 22,278 Other assets ​ ​ 162,316 ​ 150,894 Total assets $ 2,301,914 $ 2,166,435 ​ ​ ​ ​ ​ ​ ​ Third party debt, net ​ $ 1,193,327 ​ $ 1,188,710 Liabilities held for sale ​ — ​ 55,440 Accounts payable and accrued liabilities ​ ​ 71,859 ​ ​ 40,556 Total liabilities ​ 1,265,186 ​ 1,284,706 Total equity $ 1,036,728 $ 881,729
Schedule of combined financial information relating to unconsolidated joint ventures and partnerships operations (not just proportionate share)	Combined summary financial information relating to the unconsolidated joint ventures’ and partnerships’ operations (not just our proportionate share) is presented below for the three months ended March 31, 2021 and 2020 ( dollars in thousands : ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ ​ March 31, ​ 2021 2020 Total revenues $ 32,137 $ 41,314 Property operating expenses ​ 17,110 ​ 15,297 Real estate depreciation and amortization ​ 16,453 ​ 16,243 Gain/(loss) on sale of property ​ ​ 34,757 ​ ​ — Operating income/(loss) ​ 33,331 ​ ​ 9,774 Interest expense ​ (12,134) ​ (10,347) Net realized/unrealized gain/(loss) on held investments ​ ​ 8,488 ​ ​ — Other income/(loss) ​ ​ (1,657) ​ ​ (8) Net income/(loss) $ 28,028 $ (581)

LEASES (Tables)

LEASES (Tables)	3 Months Ended
	Mar. 31, 2021
LEASES
Lessee - Future minimum lease payments and total operating lease liabilities	Future minimum lease payments and total operating lease liabilities from our ground leases as of March 31, 2021 are as follows (dollars in thousands): ​ ​ ​ ​ ​ ​ Ground Leases 2021 ​ $ 9,331 2022 ​ ​ 12,442 2023 ​ ​ 12,442 2024 ​ ​ 12,442 2025 ​ ​ 12,442 Thereafter ​ ​ 442,778 Total future minimum lease payments (undiscounted) ​ ​ 501,877 Difference between future undiscounted cash flows and discounted cash flows ​ ​ (307,048) Total operating lease liabilities (discounted) ​ $ 194,829
Lessee - components of operating lease expenses	The components of operating lease expenses were as follows (dollars in thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended March 31, ​ ​ 2021 ​ 2020 Lease expense: ​ ​ ​ ​ ​ ​ Contractual lease expense ​ $ 3,230 ​ $ 3,170 Variable lease expense (a) ​ ​ 29 ​ ​ 43 Total operating lease expense (b)(c) ​ $ 3,259 ​ $ 3,213 (a) Variable lease expense includes adjustments such as changes in the consumer price index and payments based on a percentage of income of the lessee. (b) Lease expense is reported within the line item Other operating expenses on the Consolidated Statements of Operations. (c) For the three months ended March 31, 2021, Operating lease right-of-use assets and Operating lease liabilities amortized by $0.8 million and $0.8 million, respectively. For the three months ended March 31, 2020, Operating lease right-of-use assets and Operating lease liabilities amortized by $0.8 million and $0.7 million, respectively. Due to the net impact of the amortization, the Company recorded less than $0.1 million and $0.1 million of total operating lease expense during the three months ended March 31, 2021 and 2020, respectively.
Lessor - Future minimum lease payments	Future minimum lease payments from our retail and commercial leases as of March 31, 2021 are as follows (dollars in thousands): ​ ​ ​ ​ ​ ​ Retail and Commercial Leases 2021 ​ $ 18,056 2022 ​ ​ 23,450 2023 ​ ​ 21,645 2024 ​ ​ 19,879 2025 ​ ​ 16,758 Thereafter ​ ​ 71,357 Total future minimum lease payments (a) ​ $ 171,145 (a)

SECURED AND UNSECURED DEBT, N_2

SECURED AND UNSECURED DEBT, NET (Tables)	3 Months Ended
	Mar. 31, 2021
Unsecured Debt
Schedule of debt instruments	The following is a summary of our secured and unsecured debt at March 31, 2021 and December 31, 2020 ( dollars in thousands ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Principal Outstanding ​ As of March 31, 2021 ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ Weighted ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Average ​ Average ​ Number of ​ ​ March 31, ​ December 31, ​ Interest ​ Years to ​ Communities ​ 2021 2020 Rate Maturity Encumbered Secured Debt: ​ ​ ​ ​ ​ ​ ​ Fixed Rate Debt ​ ​ Mortgage notes payable (a) ​ $ 876,080 ​ $ 824,550 3.37 % 7.0 12 Deferred financing costs and other non-cash adjustments (b) ​ 16,162 ​ 10,665 Total fixed rate secured debt, net ​ 892,242 ​ 835,215 3.37 % 7.0 12 Variable Rate Debt ​ ​ Tax-exempt secured notes payable (c) ​ 27,000 ​ 27,000 0.77 % 11.0 1 Deferred financing costs ​ (65) ​ (68) Total variable rate secured debt, net ​ 26,935 ​ 26,932 0.77 % 11.0 1 Total Secured Debt, net ​ 919,177 ​ 862,147 3.29 % 7.1 13 Unsecured Debt: ​ ​ Variable Rate Debt ​ ​ Borrowings outstanding under unsecured credit facility due January 2023 (d) (o) ​ — ​ — — % 1.8 Borrowings outstanding under unsecured commercial paper program due April 2021 (e) (o) ​ ​ 210,000 ​ ​ 190,000 ​ 0.26 % 0.1 ​ ​ Borrowings outstanding under unsecured working capital credit facility due January 2022 ​ 17,813 ​ 28,024 0.94 % 0.8 Term Loan due September 2023 (d) (o) ​ 35,000 ​ 35,000 1.02 % 2.5 Fixed Rate Debt ​ ​ Term Loan due September 2023 (d) (o) ​ ​ 315,000 ​ 315,000 1.07 % 2.5 ​ ​ 8.50% Debentures due September 2024 ​ 15,644 ​ 15,644 8.50 % 3.5 4.00% Medium-Term Notes due October 2025 (net of discounts of $0 and $327, respectively) (g) (o) ​ — ​ 299,673 — % — 2.95% Medium-Term Notes due September 2026 (h) (o) ​ 300,000 ​ 300,000 2.89 % 5.4 3.50% Medium-Term Notes due July 2027 (net of discounts of $441 and $458, respectively) (i) (o) ​ ​ 299,559 ​ ​ 299,542 ​ 4.03 % 6.3 ​ ​ 3.50% Medium-Term Notes due January 2028 (net of discounts of $806 and $835, respectively) (o) ​ ​ 299,194 ​ ​ 299,165 ​ 3.50 % 6.8 ​ ​ 4.40% Medium-Term Notes due January 2029 (net of discounts of $5 and $5, respectively) (j) (o) ​ ​ 299,995 ​ ​ 299,995 ​ 4.27 % 7.8 ​ ​ 3.20% Medium-Term Notes due January 2030 (net of premiums of $12,070 and $12,412, respectively) (k) (o) ​ ​ 612,070 ​ ​ 612,412 ​ 3.32 % 8.8 ​ ​ 3.00% Medium-Term Notes due August 2031 (net of discounts of $1,003 and $1,027, respectively) (l) (o) ​ ​ 398,997 ​ ​ 398,973 ​ 3.01 % 10.4 ​ ​ 2.10% Medium-Term Notes due August 2032 (net of discounts of $399 and $408, respectively) (o) ​ ​ 399,601 ​ ​ 399,592 ​ 2.10 % 11.3 ​ ​ 1.90% Medium-Term Notes due March 2033 (net of discounts of $1,440 and $1,471, respectively) (o) ​ ​ 348,560 ​ ​ 348,529 ​ 1.90 % 12.0 ​ ​ 2.10% Medium-Term Notes due June 2033 (net of discounts of $1,215 and $0, respectively) (m) (o) ​ ​ 298,785 ​ ​ — ​ 2.10 % 12.2 ​ ​ 3.10% Medium-Term Notes due November 2034 (net of discounts of $1,199 and $1,221, respectively) (n) (o) ​ ​ 298,801 ​ ​ 298,779 ​ 3.13 % 13.6 ​ ​ Other ​ 9 ​ 10 Deferred financing costs ​ (27,030) ​ (25,937) Total Unsecured Debt, net ​ 4,121,998 ​ 4,114,401 2.72 % 8.4 Total Debt, net ​ $ 5,041,175 ​ $ 4,976,548 2.84 % 8.2
Schedule of aggregate maturities, including amortizing principal payments of secured and unsecured debt	The aggregate maturities, including amortizing principal payments on secured and unsecured debt, of total debt for the next ten calendar years subsequent to March 31, 2021 are as follows (dollars in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total Fixed Total Variable Total Total Total Year ​ Secured Debt ​ Secured Debt ​ Secured Debt ​ Unsecured Debt ​ Debt 2021 ​ $ 827 ​ $ — ​ $ 827 ​ $ 210,000 (a) $ 210,827 2022 ​ ​ 1,140 ​ ​ — ​ ​ 1,140 ​ ​ 17,813 ​ ​ 18,953 2023 ​ 1,183 ​ — ​ 1,183 ​ 350,000 ​ 351,183 2024 ​ 96,028 ​ — ​ 96,028 ​ 15,644 ​ 111,672 2025 ​ 174,043 ​ — ​ 174,043 ​ — ​ 174,043 2026 ​ 51,963 ​ — ​ 51,963 ​ 300,000 ​ 351,963 2027 ​ 2,045 ​ — ​ 2,045 ​ 300,000 ​ 302,045 2028 ​ 123,435 ​ — ​ 123,435 ​ 300,000 ​ 423,435 2029 ​ 191,986 ​ — ​ 191,986 ​ 300,000 ​ 491,986 2030 ​ 72,500 ​ — ​ 72,500 ​ 600,000 ​ 672,500 Thereafter ​ 160,930 ​ 27,000 ​ 187,930 ​ 1,750,000 ​ 1,937,930 Subtotal ​ 876,080 ​ 27,000 ​ 903,080 ​ 4,143,457 ​ 5,046,537 Non-cash (b) ​ 16,162 ​ (65) ​ 16,097 ​ (21,459) ​ (5,362) Total ​ $ 892,242 ​ $ 26,935 ​ $ 919,177 ​ $ 4,121,998 ​ $ 5,041,175 (a) All unsecured debt due in the remainder of 2021 is related to the Company’s commercial paper program. (b) Includes the unamortized balance of fair market value adjustments, premiums/discounts and deferred financing costs . The Company amortized $1.2 million and $1.0 million, respectively, during the three months ended March 31, 2021 and 2020, of deferred financing costs into Interest expense.
Commercial Paper
Unsecured Debt
Schedule of short-term debt	The following is a summary of short-term bank borrowings under the unsecured commercial paper program at March 31, 2021 and December 31, 2020 (dollars in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, December 31, ​ ​ 2021 ​ 2020 Total unsecured commercial paper program $ 500,000 ​ $ 500,000 ​ Borrowings outstanding at end of period ​ 210,000 ​ 190,000 ​ Weighted average daily borrowings during the period ended ​ 191,389 ​ 227,090 ​ Maximum daily borrowings during the period ended ​ 340,000 ​ 500,000 ​ Weighted average interest rate during the period ended ​ 0.3 % 0.9 % Interest rate at end of the period ​ 0.3 % 0.3 %
Revolving Credit Facility
Unsecured Debt
Schedule of short-term debt	The following is a summary of short-term bank borrowings under the Revolving Credit Facility at March 31, 2021 and December 31, 2020 (dollars in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, December 31, ​ ​ 2021 2020 ​ Total revolving credit facility ​ $ 1,100,000 ​ $ 1,100,000 ​ Borrowings outstanding at end of period (1) ​ — ​ — ​ Weighted average daily borrowings during the period ended ​ — ​ 42,186 ​ Maximum daily borrowings during the period ended ​ — ​ 375,000 ​ Weighted average interest rate during the period ended ​ — % 1.4 % Interest rate at end of the period ​ — % — % (1) Excludes $2.3 million and $2.8 million of letters of credit at March 31, 2021 and December 31, 2020, respectively .
Unsecured Working Capital Credit Facility
Unsecured Debt
Schedule of short-term debt	The following is a summary of short-term bank borrowings under the Working Capital Credit Facility at March 31, 2021 and December 31, 2020 (dollars in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, December 31, ​ ​ 2021 ​ 2020 Total working capital credit facility ​ $ 75,000 ​ $ 75,000 ​ Borrowings outstanding at end of period ​ 17,813 ​ 28,024 ​ Weighted average daily borrowings during the period ended ​ 7,438 ​ 20,132 ​ Maximum daily borrowings during the period ended ​ 37,560 ​ 54,974 ​ Weighted average interest rate during the period ended ​ 0.9 % 1.4 % Interest rate at end of the period ​ 0.9 % 1.0 %

INCOME_(LOSS) PER SHARE (Tables

INCOME/(LOSS) PER SHARE (Tables)	3 Months Ended
	Mar. 31, 2021
INCOME/(LOSS) PER SHARE
Computation of basic and diluted income/(loss) per share	The following table sets forth the computation of basic and diluted income/(loss) per share for the periods presented (dollars and shares in thousands, except per share data): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ ​ ​ March 31, ​ ​ 2021 2020 ​ Numerator for income/(loss) per share: ​ ​ ​ ​ ​ ​ Net income/(loss) ​ $ 3,274 ​ $ 5,540 ​ Net (income)/loss attributable to redeemable noncontrolling interests in the Operating Partnership and DownREIT Partnership ​ (154) ​ (313) ​ Net (income)/loss attributable to noncontrolling interests ​ (16) ​ (6) ​ Net income/(loss) attributable to UDR, Inc. ​ 3,104 ​ 5,221 ​ Distributions to preferred stockholders — Series E (Convertible) ​ (1,056) ​ (1,066) ​ Income/(loss) attributable to common stockholders - basic and diluted ​ $ 2,048 ​ $ 4,155 ​ ​ ​ ​ ​ ​ ​ ​ ​ Denominator for income/(loss) per share: ​ ​ ​ Weighted average common shares outstanding ​ 296,800 ​ 294,731 ​ Non-vested restricted stock awards ​ (263) ​ (274) ​ Denominator for basic income/(loss) per share ​ 296,537 ​ 294,457 ​ Incremental shares issuable from assumed conversion of unvested LTIP Units and unvested restricted stock ​ 489 ​ 703 ​ Denominator for diluted income/(loss) per share ​ 297,026 ​ 295,160 ​ ​ ​ ​ ​ ​ ​ ​ ​ Income/(loss) per weighted average common share: ​ ​ ​ Basic ​ $ 0.01 ​ $ 0.01 ​ Diluted ​ $ 0.01 ​ $ 0.01 ​
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share	The following table sets forth the additional shares of common stock outstanding, by equity instrument, if converted to common stock for each of the three months ended March 31, 2021 and 2020 (in thousands) ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ ​ ​ March 31, ​ ​ ​ 2021 ​ 2020 ​ OP/DownREIT Units 22,398 22,228 Convertible preferred stock 2,918 3,011 Unvested LTIP Units and unvested restricted stock 489 703

NONCONTROLLING INTERESTS (Table

NONCONTROLLING INTERESTS (Tables)	3 Months Ended
	Mar. 31, 2021
NONCONTROLLING INTERESTS
Redeemable noncontrolling interests in the Operating Partnership and DownREIT Partnership	The following table sets forth redeemable noncontrolling interests in the Operating Partnership and DownREIT Partnership for the following period ( dollars in thousands ​ ​ ​ ​ ​ Redeemable noncontrolling interests in the Operating Partnership and DownREIT Partnership, December 31, 2020 $ 856,294 ​ Mark-to-market adjustment to redeemable noncontrolling interests in the Operating Partnership and DownREIT Partnership ​ 131,700 ​ Conversion of OP Units/DownREIT Units to Common Stock ​ (4,497) ​ Net income/(loss) attributable to redeemable noncontrolling interests in the Operating Partnership and DownREIT Partnership ​ 154 ​ Distributions to redeemable noncontrolling interests in the Operating Partnership and DownREIT Partnership ​ (8,586) ​ Vesting of Long-Term Incentive Plan Units ​ ​ 14,578 ​ Allocation of other comprehensive income/(loss) ​ 43 ​ Redeemable noncontrolling interests in the Operating Partnership and DownREIT Partnership, March 31, 2021 ​ $ 989,686 ​

FAIR VALUE OF DERIVATIVES AND_2

FAIR VALUE OF DERIVATIVES AND FINANCIAL INSTRUMENTS (Tables)	3 Months Ended
	Mar. 31, 2021
FAIR VALUE OF DERIVATIVES AND FINANCIAL INSTRUMENTS
Schedule of estimated fair values	The estimated fair values of the Company’s financial instruments either recorded or disclosed on a recurring basis as of March 31, 2021 and December 31, 2020, are summarized as follows (dollars in thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value at March 31, 2021, Using ​ ​ Total ​ ​ ​ Quoted ​ ​ ​ ​ ​ ​ Carrying ​ ​ ​ Prices in ​ ​ ​ ​ ​ ​ Amount in ​ ​ ​ Active ​ ​ ​ ​ ​ ​ ​ Statement of ​ ​ ​ ​ Markets ​ Significant ​ ​ ​ ​ ​ Financial ​ Fair Value ​ for Identical ​ Other ​ Significant ​ ​ Position at ​ Estimate at ​ Assets or ​ Observable ​ Unobservable ​ ​ March 31, ​ March 31, ​ Liabilities ​ Inputs ​ Inputs ​ ​ 2021 (a) ​ 2021 ​ (Level 1) ​ (Level 2) ​ (Level 3) Description: ​ ​ ​ ​ ​ ​ Notes receivable, net (b) ​ $ 155,206 ​ $ 169,001 ​ $ — ​ $ — ​ $ 169,001 Derivatives - Interest rate contracts (c) ​ 9 ​ 9 ​ — ​ 9 ​ — Total assets ​ $ 155,215 ​ $ 169,010 ​ $ — ​ $ 9 ​ $ 169,001 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Derivatives - Interest rate contracts (c) ​ $ 67 ​ $ 67 ​ $ — ​ $ 67 ​ $ — Secured debt instruments - fixed rate: (d) ​ ​ ​ ​ ​ ​ Mortgage notes payable ​ ​ 894,967 ​ ​ 898,675 ​ ​ — ​ ​ — ​ ​ 898,675 Secured debt instruments - variable rate: (d) ​ ​ ​ ​ ​ ​ Tax-exempt secured notes payable ​ 27,000 ​ 27,000 ​ — ​ — ​ 27,000 Unsecured debt instruments: (d) ​ ​ ​ ​ ​ ​ Working capital credit facility ​ ​ 17,813 ​ ​ 17,813 ​ ​ — ​ ​ — ​ ​ 17,813 Commercial paper program ​ ​ 210,000 ​ ​ 210,000 ​ ​ — ​ ​ — ​ ​ 210,000 Unsecured notes ​ ​ 3,921,215 ​ ​ 3,983,183 ​ ​ — ​ ​ — ​ ​ 3,983,183 Total liabilities ​ $ 5,071,062 ​ $ 5,136,738 ​ $ — ​ $ 67 ​ $ 5,136,671 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Redeemable noncontrolling interests in the Operating Partnership and DownREIT Partnership (e) ​ $ 989,686 ​ $ 989,686 ​ $ — ​ $ 989,686 ​ $ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value at December 31, 2020, Using ​ ​ Total ​ ​ ​ Quoted ​ ​ ​ ​ ​ ​ Carrying ​ ​ ​ Prices in ​ ​ ​ ​ ​ ​ Amount in ​ ​ ​ Active ​ ​ ​ ​ ​ ​ Statement of ​ ​ ​ Markets ​ Significant ​ ​ ​ ​ Financial ​ Fair Value ​ for Identical ​ Other ​ Significant ​ ​ Position at ​ Estimate at ​ Assets or ​ Observable ​ Unobservable ​ ​ December 31, ​ December 31, ​ Liabilities ​ Inputs ​ Inputs ​ 2020 (a) ​ 2020 ​ (Level 1) ​ (Level 2) ​ (Level 3) Description: ​ ​ ​ ​ ​ ​ Notes receivable, net (b) ​ $ 157,992 ​ $ 170,411 ​ $ — ​ $ — ​ $ 170,411 Derivatives - Interest rate contracts (c) ​ 2 ​ 2 ​ — ​ 2 ​ — Total assets ​ $ 157,994 ​ $ 170,413 ​ $ — ​ $ 2 ​ $ 170,411 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Derivatives - Interest rate contracts (c) ​ $ 167 ​ $ 167 ​ $ — ​ $ 167 ​ $ — Secured debt instruments - fixed rate: (d) ​ ​ ​ ​ ​ ​ Mortgage notes payable ​ ​ 837,473 ​ ​ 854,084 ​ ​ — ​ ​ — ​ ​ 854,084 Secured debt instruments - variable rate: (d) ​ ​ ​ ​ ​ ​ Tax-exempt secured notes payable ​ 27,000 ​ 27,000 ​ — ​ — ​ 27,000 Unsecured debt instruments: (d) ​ ​ ​ ​ ​ ​ ​ Working capital credit facility ​ ​ 28,024 ​ ​ 28,024 ​ ​ — ​ ​ — ​ ​ 28,024 Commercial paper program ​ ​ 190,000 ​ ​ 190,000 ​ ​ — ​ ​ — ​ ​ 190,000 Unsecured notes ​ ​ 3,922,314 ​ ​ 4,283,045 ​ ​ — ​ ​ — ​ ​ 4,283,045 Total liabilities ​ $ 5,004,978 ​ $ 5,382,320 ​ $ — ​ $ 167 ​ $ 5,382,153 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Redeemable noncontrolling interests in the Operating Partnership and DownREIT Partnership (e) ​ $ 856,294 ​ $ 856,294 ​ $ — ​ $ 856,294 ​ $ — (a) Balances include fair market value adjustments and exclude deferred financing costs. (b) See Note 2, Significant Accounting Policies . (c) See Note 11, Derivatives and Hedging Activity . (d) See Note 7, Secured and Unsecured Debt, Net . (e) See Note 9, Noncontrolling Interests.

DERIVATIVES AND HEDGING ACTIV_2

DERIVATIVES AND HEDGING ACTIVITY (Tables)	3 Months Ended
	Mar. 31, 2021
DERIVATIVES AND HEDGING ACTIVITY
Schedule of outstanding interest rate derivatives	As of March 31, 2021, the Company had the following outstanding interest rate derivatives that were designated as cash flow hedges of interest rate risk ( dollars in thousands ​ ​ ​ ​ ​ ​ ​ Number of ​ Product ​ Instruments ​ Notional Interest rate swaps and caps ​ 4 ​ $ 334,880
Fair value of Company's derivative financial instruments and their classification on Consolidated Balance Sheets	The table below presents the fair value of the Company’s derivative financial instruments as well as their classification on the Consolidated Balance Sheets as of March 31, 2021 and December 31, 2020 ( dollars in thousands ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Asset Derivatives ​ Liability Derivatives ​ ​ (included in Other assets ) ​ (included in Other liabilities ) ​ ​ Fair Value at: ​ Fair Value at: ​ ​ March 31, ​ December 31, ​ March 31, ​ December 31, ​ ​ 2021 ​ 2020 ​ 2021 ​ 2020 Derivatives designated as hedging instruments: ​ ​ ​ ​ Interest rate products ​ $ 9 ​ $ 2 ​ $ 67 ​ $ 167
Effect of Company's derivative financial instruments on Consolidated Statements of Operations	The tables below present the effect of the Company’s derivative financial instruments on the Consolidated Statements of Operations for the three months ended March 31, 2021 and 2020 ( dollars in thousands ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Gain/(Loss) Recognized in ​ ​ ​ ​ Gain/(Loss) Reclassified ​ Interest expense ​ ​ Unrealized holding gain/(loss) ​ from Accumulated OCI into ​ (Amount Excluded from ​ ​ Recognized in OCI ​ Interest expense ​ Effectiveness Testing) Derivatives in Cash Flow Hedging Relationships 2021 2020 2021 2020 2021 2020 Three Months Ended March 31, ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Interest rate products ​ $ 127 ​ $ (2,917) ​ $ (446) ​ $ (357) ​ $ — ​ $ —
Effect of Company's derivatives not designated as hedging instruments on the Consolidated Statements of Operations	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ ​ March 31, ​ ​ 2021 ​ 2020 Total amount of Interest expense ​ $ 78,156 ​ $ 39,317 ​
Offsetting of Derivative Assets	The Company has elected not to offset derivative positions on the consolidated financial statements. The tables below present the effect on its financial position had the Company made the election to offset its derivative positions as of March 31, 2021 and December 31, 2020 (dollars in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Gross Net Amounts of Gross Amounts Not Offset ​ ​ ​ ​ ​ ​ ​ ​ Amounts ​ Assets ​ in the Consolidated ​ ​ ​ ​ ​ Gross ​ Offset in the ​ Presented in the ​ Balance Sheet ​ ​ ​ ​ ​ Amounts of ​ Consolidated ​ Consolidated ​ ​ ​ ​ Cash ​ ​ ​ ​ ​ Recognized ​ Balance ​ Balance Sheets ​ Financial ​ Collateral ​ ​ ​ Offsetting of Derivative Assets ​ Assets ​ Sheets ​ (a) ​ Instruments Received Net Amount March 31, 2021 ​ $ 9 ​ $ — ​ $ 9 ​ $ — ​ $ — ​ $ 9 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2020 ​ $ 2 ​ $ — ​ $ 2 ​ $ — ​ $ — ​ $ 2 (a) Amounts reconcile to the aggregate fair value of derivative assets in the “Tabular Disclosure of Fair Values of Derivative Instruments on the Consolidated Balance Sheets” located in this footnote.
Offsetting of Derivative Liabilities	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Gross Net Amounts of Gross Amounts Not Offset ​ ​ ​ ​ ​ ​ ​ ​ Amounts ​ Liabilities ​ in the Consolidated ​ ​ ​ ​ ​ Gross ​ Offset in the ​ Presented in the ​ Balance Sheet ​ ​ ​ ​ ​ Amounts of ​ Consolidated ​ Consolidated ​ ​ ​ ​ Cash ​ ​ ​ ​ ​ Recognized ​ Balance ​ Balance Sheets ​ Financial ​ Collateral ​ ​ ​ Offsetting of Derivative Liabilities Liabilities Sheets (a) Instruments Posted Net Amount March 31, 2021 ​ $ 67 ​ $ — ​ $ 67 ​ $ — ​ $ — ​ $ 67 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2020 ​ $ 167 ​ $ — ​ $ 167 ​ $ — ​ $ — ​ $ 167 (a) Amounts reconcile to the aggregate fair value of derivative liabilities in the “Tabular Disclosure of Fair Values of Derivative Instruments on the Consolidated Balance Sheets” located in this footnote.

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Tables)	3 Months Ended
	Mar. 31, 2021
COMMITMENTS AND CONTINGENCIES
Summary of real estate commitments	The following summarizes the Company’s real estate commitments at March 31, 2021 ( dollars in thousands ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Number ​ UDR's ​ UDR's Remaining ​ ​ ​ Properties ​ Investment (a) ​ Commitment ​ Wholly-owned — under development 5 ​ $ 243,200 ​ $ 258,300 Joint ventures: ​ ​ Preferred equity investments 2 ​ ​ 7,082 (b) ​ 43,104 (b) Real estate technology investments: ​ ​ ​ ​ ​ ​ ​ ​ ​ RETV I ​ - ​ ​ 22,641 ​ ​ 5,220 ​ RETV II ​ - ​ ​ 2,184 ​ ​ 14,025 ​ Total ​ $ 275,107 ​ $ 301,404 (a) Represents UDR’s investment as of March 31, 2021. (b) Represents UDR’s investment in and remaining commitment for Makers Rise and 121 at Watters, which are under development as of March 31, 2021.

REPORTABLE SEGMENTS (Tables)

REPORTABLE SEGMENTS (Tables)	3 Months Ended
	Mar. 31, 2021
REPORTABLE SEGMENTS
Summary of rental income and NOI for UDRs reportable segments and reconciliation of NOI to Net income/(loss)	The following table details rental income and NOI for UDR’s reportable segments for the three months ended March 31, 2021 and 2020, and reconciles NOI to Net income/(loss) attributable to UDR, Inc. (dollars in thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ ​ March 31, (a) ​ 2021 2020 Reportable apartment home segment lease revenue ​ ​ ​ ​ ​ ​ Same-Store Communities (a) ​ ​ ​ West Region ​ $ 100,170 ​ $ 111,215 Mid-Atlantic Region ​ 59,917 ​ 62,537 Northeast Region ​ 52,050 ​ 57,495 Southeast Region ​ 34,637 ​ 33,781 Southwest Region ​ 23,211 ​ 23,815 Non-Mature Communities/Other ​ 21,460 ​ 22,779 Total segment and consolidated lease revenue ​ $ 291,445 ​ $ 311,622 ​ ​ ​ ​ ​ ​ ​ Reportable apartment home segment other revenue ​ ​ ​ ​ ​ ​ Same-Store Communities (a) ​ ​ ​ West Region ​ $ 2,718 ​ $ 2,930 Mid-Atlantic Region ​ 1,702 ​ 1,701 Northeast Region ​ 1,047 ​ 1,064 Southeast Region ​ 1,493 ​ 1,524 Southwest Region ​ 875 ​ 820 Non-Mature Communities/Other ​ 546 ​ 432 Total segment and consolidated other revenue ​ $ 8,381 ​ $ 8,471 ​ ​ ​ ​ ​ ​ ​ Total reportable apartment home segment rental income ​ ​ ​ ​ ​ ​ Same-Store Communities (a) ​ ​ ​ West Region ​ $ 102,888 ​ $ 114,145 Mid-Atlantic Region ​ 61,619 ​ 64,238 Northeast Region ​ 53,097 ​ 58,559 Southeast Region ​ 36,130 ​ 35,305 Southwest Region ​ 24,086 ​ 24,635 Non-Mature Communities/Other ​ 22,006 ​ 23,211 Total segment and consolidated rental income ​ $ 299,826 ​ $ 320,093 ​ ​ ​ ​ ​ ​ ​ Reportable apartment home segment NOI ​ ​ Same-Store Communities (a) ​ ​ West Region ​ $ 74,845 ​ $ 86,091 Mid-Atlantic Region ​ 42,402 ​ 45,317 Northeast Region ​ 33,343 ​ 40,323 Southeast Region ​ 24,317 ​ 24,537 Southwest Region ​ 14,834 ​ 15,383 Non-Mature Communities/Other ​ 11,317 ​ 13,814 Total segment and consolidated NOI ​ 201,058 ​ 225,465 Reconciling items: ​ ​ Joint venture management and other fees ​ 1,615 ​ 1,388 Property management ​ (8,995) ​ (9,203) Other operating expenses ​ (4,435) ​ (4,966) Real estate depreciation and amortization ​ (144,088) ​ (155,476) General and administrative ​ (12,736) ​ (14,978) Casualty-related (charges)/recoveries, net ​ (5,577) ​ (1,251) Other depreciation and amortization ​ (2,601) ​ (2,025) Gain/(loss) on sale of real estate owned ​ ​ 50,829 ​ ​ — Income/(loss) from unconsolidated entities ​ 4,922 ​ 3,367 Interest expense ​ (78,156) ​ (39,317) Interest income and other income/(expense), net ​ 2,057 ​ 2,700 Tax (provision)/benefit, net ​ (619) ​ (164) Net (income)/loss attributable to redeemable noncontrolling interests in the Operating Partnership and DownREIT Partnership ​ (154) ​ (313) Net (income)/loss attributable to noncontrolling interests ​ (16) ​ (6) Net income/(loss) attributable to UDR, Inc. ​ $ 3,104 ​ $ 5,221 (a) Same-Store Community population consisted of 45,403 apartment homes. ​
Details of assets of UDR's reportable segments	The following table details the assets of UDR’s reportable segments as of March 31, 2021 and December 31, 2020 (dollars in thousands) ​ ​ ​ ​ ​ ​ ​ ​ March 31, December 31, ​ ​ 2021 ​ 2020 Reportable apartment home segment assets: ​ ​ Same-Store Communities (a): ​ ​ West Region ​ $ 4,255,427 ​ $ 4,247,900 Mid-Atlantic Region ​ 2,703,939 ​ 2,698,049 Northeast Region ​ 2,904,450 ​ 2,900,017 Southeast Region ​ 978,568 ​ 974,754 Southwest Region ​ 896,728 ​ 897,505 Non-Mature Communities/Other ​ 1,356,788 ​ 1,353,247 Total segment assets ​ 13,095,900 ​ 13,071,472 Accumulated depreciation ​ (4,730,021) ​ (4,605,366) Total segment assets — net book value ​ 8,365,879 ​ 8,466,106 Reconciling items: ​ ​ Cash and cash equivalents ​ 1,172 ​ 1,409 Restricted cash ​ 33,428 ​ 22,762 Notes receivable, net ​ 155,206 ​ 157,992 Investment in and advances to unconsolidated joint ventures, net ​ 620,111 ​ 600,233 Operating lease right-of-use assets ​ ​ 200,064 ​ ​ 200,913 Other assets ​ 190,696 ​ 188,118 Total consolidated assets ​ $ 9,566,556 ​ $ 9,637,533 (a) Same-Store Community population consisted of 45,403 apartment homes. ​

BASIS OF PRESENTATION (Details)

BASIS OF PRESENTATION (Details) shares in Millions	Mar. 31, 2021homecommunityshares
Consolidation And Basis Of Presentation
Number of Real Estate Properties | community	150
Number Of Apartment Homes Owned And Consolidated By Company | home	48,363
Operating Partnership outstanding units	185.2
United Dominion Realty L.P.
Consolidation And Basis Of Presentation
Operating Partnership units outstanding related to limited partner	176.2
General Partnership units outstanding	0.1
General Partners' ownership (as a percent)	95.10%
UDR Lighthouse DownREIT L.P.
Consolidation And Basis Of Presentation
Operating Partnership outstanding units	32.4
Non-affiliated Partners
Consolidation And Basis Of Presentation
Operating Partnership units outstanding related to limited partner	9
Percentage of units outstanding in Partnership	4.90%
Non-affiliated Partners | UDR Lighthouse DownREIT L.P.
Consolidation And Basis Of Presentation
Operating Partnership outstanding units	13.6
Percentage of units outstanding in Partnership	42.00%
UDR, Inc.
Consolidation And Basis Of Presentation
General Partners' ownership (as a percent)	58.00%
Operating Partnership outstanding units	18.8

SIGNIFICANT ACCOUNTING POLICI_4

SIGNIFICANT ACCOUNTING POLICIES (Details) $ in Thousands	1 Months Ended	3 Months Ended
	Nov. 30, 2019USD ($)home	Mar. 31, 2021USD ($)	Mar. 31, 2020USD ($)	Jan. 31, 2021USD ($)	Dec. 31, 2020USD ($)	May 31, 2020USD ($)
Accounting policies
Notes receivable		$ 155,885			$ 158,685
Allowance for credit losses		(679)			(693)
Notes receivable, net		155,206			157,992
Significant Accounting Policies
Note receivable interest income		1,900	$ 2,600
Interest Income, Related Party		0	0
Allocation of other comprehensive income/(loss)		43
Current Income Tax Expense (Benefit)		0
Net deferred tax assets/(liabilities)		(600)			(3,200)
Unrecognized tax benefit, accrued interest or penalties due to examination		0
Adjustment to rental income		5,100
Adjustment to income (loss)		400
Noncontrolling Interests
Significant Accounting Policies
Allocation of other comprehensive income/(loss)			(100)
Maximum
Significant Accounting Policies
Credit losses/(recoveries)		(100)	$ 100
Maximum | Noncontrolling Interests
Significant Accounting Policies
Allocation of other comprehensive income/(loss)		100
Bellevue, WA 259 Home Community
Significant Accounting Policies
Number of apartment homes | home	259
Note due April 2020
Accounting policies
Notes receivable		$ 20,000
Note due February 2021
Accounting policies
Notes receivable				$ 4,000	4,000	$ 4,000
Note due May 2022
Accounting policies
Note receivable interest rate		8.00%
Notes receivable		$ 20,000			20,000
Note due October 2022
Accounting policies
Note receivable interest rate		4.75%
Notes receivable		$ 115,000			115,000
Note due October 2022 | Bellevue, WA 259 Home Community
Significant Accounting Policies
Aggregate commitment on note receivable	$ 115,000
Purchase Option Agreement, Deposit Made	10,000
Payment to acquire real estate	$ 170,000
Maturity date extension term	10 years
Loan interest term	3 years
Amortization schedule term	30 years
Note due January 2023
Accounting policies
Note receivable interest rate		10.00%
Notes receivable		$ 20,885			19,685
Notes receivable, net		20,900
Significant Accounting Policies
Aggregate commitment on note receivable		22,000		$ 22,000	$ 20,000
Note maturity public capital threshold		5,000
Additional amount loaned		1,200
Multifamily tenant lease
Significant Accounting Policies
Increase in reserves		4,700
Retail tenant lease
Significant Accounting Policies
Increase in reserves		$ 800

REAL ESTATE OWNED - Summarizes

REAL ESTATE OWNED - Summarizes the carrying amounts for our real estate owned (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Real estate owned
Land	$ 2,148,977	$ 2,139,765
Depreciable property - held and used:
Land improvements	235,002	233,823
Building, improvements, and furniture, fixtures and equipment	10,428,151	10,292,782
Real estate intangible assets	40,570	40,570
Under development:
Real estate under development	242,881	246,867
Real estate owned	13,095,900	13,071,472
Accumulated depreciation	(4,730,021)	(4,605,366)
Total real estate owned, net of accumulated depreciation	8,365,879	8,466,106
Accumulated amortization	6,500	6,500
Land and land improvements
Under development:
Real estate under development	74,399	73,702
Real estate held for disposition		15,184
Building, improvements and furniture, fixtures and equipment
Under development:
Real estate under development	$ 168,801	174,175
Real estate held for disposition		$ 101,471

REAL ESTATE OWNED - Additional

REAL ESTATE OWNED - Additional Information (Details) $ in Thousands	1 Months Ended			3 Months Ended
	Apr. 30, 2021USD ($)home	Feb. 28, 2021USD ($)home	Jan. 31, 2021USD ($)home	Mar. 31, 2021USD ($)statecommunityhome	Mar. 31, 2020USD ($)	Dec. 31, 2020USD ($)
Real Estate Owned Disclosure
Number of real estate properties | community				150
Number of states in which there are owned and consolidated communities | state				13
Number of apartment homes owned and consolidated | home				48,363
Gain/(loss) on sale of property				$ 50,829
Debt premium				18,900		$ 12,900
In-place intangibles				40,570		$ 40,570
Long-term Debt				5,046,537
Development costs excluding direct costs and capitalized interest				4,600	$ 6,900
Interest capitalized during period				$ 2,100	$ 1,400
386 Home Operating Community In Anaheim
Real Estate Owned Disclosure
Apartment homes sold | home		386
Proceeds from sale of real estate		$ 156,000
Gain/(loss) on sale of property		$ 50,800
300 Home Operating Community in Franklin
Real Estate Owned Disclosure
Number of apartment homes acquired | home			300
Debt premium			$ 6,600
Real estate acquired			82,000
In-place intangibles			2,000
Payment to acquire real estate			77,400
Long-term Debt			$ 51,800
636 Home Operating Community in Farmers Branch, Texas
Real Estate Owned Disclosure
Number of apartment homes acquired | home	636
Payment to acquire real estate	$ 110,000

JOINT VENTURES AND PARTNERSHI_3

JOINT VENTURES AND PARTNERSHIPS - Summary (Details) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2021USD ($)homecommunityproperty	Mar. 31, 2020USD ($)	Dec. 31, 2020USD ($)	Apr. 28, 2021	Jan. 31, 2021USD ($)	Dec. 31, 2019USD ($)
Unconsolidated entities
Number of real estate properties | community	150
Investment in unconsolidated entities			$ 615,238
Sold joint ventures and other investments in prior year		$ 1,289
Income/(loss) from investments	$ 595,486	3,367	4,922
Combined summary of balance sheets relating to unconsolidated joint ventures
Total real estate, net	8,365,879		8,466,106
Cash and cash equivalents	1,172	980	1,409			$ 8,106
Other Assets	190,696		188,118
Total assets	9,566,556		9,637,533
Accounts payable, accrued expenses, and other liabilities	104,218		110,999
Total liabilities	5,560,469		5,522,648
Total equity	3,016,401	3,478,390	3,258,591			$ 3,389,314
Financial information relating to unconsolidated joint ventures operations
Total revenues	301,441	321,481
Property operating expenses	51,381	49,483
Real estate depreciation and amortization	144,088	155,476
Gain/(loss) on sale of property	50,829
Operating income	75,070	38,954
Interest expense	(78,156)	(39,317)
Other income/(loss)	2,057	2,700
Net income/(loss)	3,274	5,540
Unconsolidated Joint Ventures
Combined summary of balance sheets relating to unconsolidated joint ventures
Total real estate, net	2,111,478		1,904,805
Real Estate Held-for-sale			88,458
Cash and cash equivalents	28,120		22,278
Other Assets	162,316		150,894
Total assets	2,301,914		2,166,435
Third party debt, net	1,193,327		1,188,710
Liabilities held for sale			55,440
Accounts payable, accrued expenses, and other liabilities	71,859		40,556
Total liabilities	1,265,186		1,284,706
Total equity	1,036,728		881,729
Financial information relating to unconsolidated joint ventures operations
Total revenues	32,137	41,314
Property operating expenses	17,110	15,297
Real estate depreciation and amortization	16,453	16,243
Gain/(loss) on sale of property	34,757
Operating income	33,331	9,774
Interest expense	(12,134)	(10,347)
Net realized/unrealized gain/(loss) on held investments	8,488
Other income/(loss)	(1,657)	(8)
Net income/(loss)	$ 28,028	(581)
Preferred Equity Investment 1200 Broadway Nashville TN
Unconsolidated entities
Rate				12.25%
Preferred Equity Investment Herndon, Virginia
Unconsolidated entities
Investment in unconsolidated entities					$ 30,200
Rate					9.00%
Preferred Equity Investment Allen, Texas
Unconsolidated entities
Number of apartment homes | home	469
Investment in unconsolidated entities	$ 19,800
Rate	9.00%
Operating Community
Unconsolidated entities
Investment in unconsolidated entities	$ 290,779		289,931
Income/(loss) from investments	$ (4,055)	(2,433)
Operating Community | Unconsolidated Joint Venture UDR Met Life I Partnership
Unconsolidated entities
Number of real estate properties | property	1
Number of apartment homes | home	150
Investment in unconsolidated entities	$ 26,001		$ 26,426
UDR's Ownership Interest	50.00%		50.00%
Income/(loss) from investments	$ (475)	(454)
Operating Community | Unconsolidated Joint Venture UDR MetLife II Partnership
Unconsolidated entities
Number of real estate properties | property	7
Number of apartment homes | home	1,250
Investment in unconsolidated entities	$ 186,312		$ 151,353
UDR's Ownership Interest	50.00%		50.00%
Income/(loss) from investments	$ (2,684)	(91)
Operating Community | Unconsolidated Joint Venture Other MetLife
Unconsolidated entities
Number of real estate properties | property	5
Number of apartment homes | home	1,437
Investment in unconsolidated entities	$ 78,155		$ 82,072
UDR's Ownership Interest	50.60%		50.60%
Income/(loss) from investments	$ (3,382)	(1,811)
Operating Community | Unconsolidated Joint Venture West Coast Development JV
Unconsolidated entities
Investment in unconsolidated entities	$ 311		$ 30,080
UDR's Ownership Interest	47.00%		47.00%
Income/(loss) from investments	$ 2,486	(77)
Development Community | Preferred Equity Investment 1532 Harrison San Francisco, CA
Unconsolidated entities
Investment in unconsolidated entities	35,069		$ 34,135
UDR Commitment	$ 24,645
Rate	11.00%
Years to Maturity	1 year 2 months 12 days
Income/(loss) from investments	$ 929	836
Participating Loan Years to Maturity	1 year 2 months 12 days
Development Community | Preferred Equity Investment 1200 Broadway Nashville TN
Unconsolidated entities
Investment in unconsolidated entities	$ 70,709		69,330
UDR Commitment	$ 55,558
Rate	8.00%
Years to Maturity	1 year 6 months
Income/(loss) from investments	$ 1,372	1,281
Participating Loan Years to Maturity	1 year 6 months
Development Community | Preferred Equity Investment 1641 Lincoln Santa Monica CA
Unconsolidated entities
Investment in unconsolidated entities	$ 12,049		11,699
UDR Commitment	$ 8,800
Rate	12.00%
Years to Maturity	1 year 3 months 18 days
Income/(loss) from investments	$ 350	314
Participating Loan Years to Maturity	1 year 3 months 18 days
Development Community | Preferred Equity Investment 1300 Fairmount Philadelphia, PA
Unconsolidated entities
Investment in unconsolidated entities	$ 60,799		59,544
UDR Commitment	$ 51,393
Rate	8.50%
Years to Maturity	2 years 4 months 24 days
Income/(loss) from investments	$ 1,255	1,166
Participating Loan Years to Maturity	2 years 4 months 24 days
Development Community | Preferred Equity Investment Essex Orlando, FL
Unconsolidated entities
Investment in unconsolidated entities	$ 17,292		16,770
UDR Commitment	$ 12,886
Rate	12.50%
Years to Maturity	2 years 4 months 24 days
Income/(loss) from investments	$ 522	466
Participating Loan Years to Maturity	2 years 4 months 24 days
Development Community | Preferred Equity Investment Modera Lake Merritt, Oakland
Unconsolidated entities
Investment in unconsolidated entities	$ 31,619		30,928
UDR Commitment	$ 27,250
Rate	9.00%
Years to Maturity	3 years
Income/(loss) from investments	$ 691	574
Participating Loan Years to Maturity	3 years
Development Community | Preferred Equity Investment Thousand Oaks, CA
Unconsolidated entities
Investment in unconsolidated entities	$ 21,278		17,919
UDR Commitment	$ 20,059
Rate	9.00%
Years to Maturity	3 years 9 months 18 days
Income/(loss) from investments	$ 438	24
Participating Loan Years to Maturity	3 years 9 months 18 days
Development Community | Preferred Equity Investment Queens, New York
Unconsolidated entities
Investment in unconsolidated entities	$ 43,737		42,360
UDR Commitment	$ 40,000
Rate	13.00%
Years to Maturity	4 years 3 months 18 days
Income/(loss) from investments	$ 1,372
Participating Loan Years to Maturity	4 years 3 months 18 days
Development Community | Preferred Equity Investment Herndon, Virginia
Unconsolidated entities
Investment in unconsolidated entities	$ 7,070
UDR Commitment	$ 30,208
Rate	9.00%
Years to Maturity	4 years 8 months 12 days
Income/(loss) from investments	$ 96
Participating Loan Years to Maturity	4 years 8 months 12 days
Development Community | Preferred Equity Investment Allen, Texas
Unconsolidated entities
Investment in unconsolidated entities	$ 12
UDR Commitment	$ 19,846
Rate	9.00%
Years to Maturity	5 years
Income/(loss) from investments	$ 2
Participating Loan Years to Maturity	5 years
Development Community | Real estate technology investments RETV I
Unconsolidated entities
Investment in unconsolidated entities	$ 22,641		20,587
UDR Commitment	18,000
Income/(loss) from investments	2,051	(150)
Development Community | Real estate technology investments RETV II
Unconsolidated entities
Investment in unconsolidated entities	2,184		2,283
UDR Commitment	16,500
Income/(loss) from investments	(101)
Development Community | Preferred Equity Investments and Real Estate Technology Investments
Unconsolidated entities
Investment in unconsolidated entities	324,459		$ 305,555
Income/(loss) from investments	$ 8,977	$ 4,511

JOINT VENTURES AND PARTNERSHI_4

JOINT VENTURES AND PARTNERSHIPS - Commitments (Details) $ in Thousands	1 Months Ended		3 Months Ended
	Apr. 28, 2021USD ($)	Jan. 31, 2021USD ($)homecommunity	Mar. 31, 2021USD ($)home	Mar. 31, 2020USD ($)	Feb. 28, 2022	Dec. 31, 2020USD ($)
Joint Ventures
Investment in unconsolidated entities						$ 615,238
Balance payments made	$ 12,500
Deferred fees from the sale of properties			$ 9,200			8,400
Gain/(loss) on sale of real estate owned			50,829
Joint venture management and other fees			$ 1,615	$ 1,388
Type of revenue			udr:ManagementAndOtherFeesMember	udr:ManagementAndOtherFeesMember
Preferred Equity Investment Herndon, Virginia
Joint Ventures
Investment in unconsolidated entities		$ 30,200
Preferred return (as a percent)		9.00%
Joint venture, number of homes in communities | home		356
Preferred Equity Investment Allen, Texas
Joint Ventures
Investment in unconsolidated entities			$ 19,800
Preferred return (as a percent)			9.00%
Number of apartment homes | home			469
Preferred Equity Investment Los Angeles, California
Joint Ventures
Number of apartment homes | community		293
Proceeds from sale of real estate		$ 121,000
Gain/(loss) on sale of real estate owned		$ 2,500
Preferred Equity Investment 1200 Broadway Nashville TN
Joint Ventures
Preferred return (as a percent)	12.25%
Preferred Equity Investment 1200 Broadway Nashville TN | Forecast
Joint Ventures
Preferred return (as a percent)					8.00%
13th and Market Properties LLC | Accounts Payable and Accrued Liabilities
Joint Ventures
Investment in unconsolidated entities			$ (4,900)			$ (4,700)

LEASES - Lessee Future Minimum

LEASES - Lessee Future Minimum Payments (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2021USD ($)community	Dec. 31, 2020USD ($)
Lease expense:
Number of communities subject to ground leases | community	6
Operating leases existence of option to extend	true
Operating lease right-of-use assets	$ 200,064	$ 200,913
Weighted average remaining lease term	43 years 9 months 18 days	43 years 10 months 24 days
Weighted average discount rate	5.00%	5.00%
Future minimum lease payments
Total operating lease liabilities (discounted)	$ 194,829	$ 195,592
LAND
Future minimum lease payments
2021	9,331
2022	12,442
2023	12,442
2024	12,442
2025	12,442
Thereafter	442,778
Total future minimum lease payments (undiscounted)	501,877
Difference between future undiscounted cash flows and discounted cash flows	(307,048)
Total operating lease liabilities (discounted)	$ 194,829

LEASES - Lessee Expenses (Detai

LEASES - Lessee Expenses (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Lease expense:
Contractual lease expense		$ 100
Variable lease expense	$ 100	100
Operating lease right-of-use asset amortization	800	800
Operating lease liabilities amortization	800	700
Maximum
Lease expense:
Contractual lease expense	100
LAND
Lease expense:
Contractual lease expense	3,230	3,170
Variable lease expense	29	43
LAND | Other operating expense
Lease expense:
Total operating lease expense	$ 3,259	$ 3,213

LEASES - Lessor (Details)

LEASES - Lessor (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Future minimum lease payments
Variable lease expense	$ 100	$ 100
LAND
Future minimum lease payments
Variable lease expense	$ 29	$ 43
Apartment Homes
Lessor leases
Percentage of lease revenue	98.60%
Option to extend	true
Apartment Homes | Maximum
Lessor leases
Lease terms	12 months
Retail and Commercial Spaces
Lessor leases
Percentage of lease revenue	1.40%
Option to extend	true
Future minimum lease payments
2021	$ 18,056
2022	23,450
2023	21,645
2024	19,879
2025	16,758
Thereafter	71,357
Total future minimum payments	$ 171,145
Retail and Commercial Spaces | Minimum
Lessor leases
Lease terms	5 years
Retail and Commercial Spaces | Maximum
Lessor leases
Lease terms	15 years

SECURED AND UNSECURED DEBT, N_3

SECURED AND UNSECURED DEBT, NET - Summary (Details) $ in Thousands	1 Months Ended	3 Months Ended
	Feb. 29, 2020	Mar. 31, 2021USD ($)community	Feb. 28, 2021	Dec. 31, 2020USD ($)	Jul. 31, 2020USD ($)
Secured debt instruments
Unamortized net premium		$ 18,900		$ 12,900
Weighted Average Interest Rate		2.84%
Total Debt, net		$ 5,041,175		4,976,548
Total Unsecured Debt, net		4,121,998		4,114,401
Borrowings outstanding		$ 2,300		2,800
Weighted Average
Secured debt instruments
Years to maturity		8 years 2 months 12 days
Fixed Rate Debt
Secured debt instruments
Principal outstanding		$ 892,242		835,215
Weighted Average Interest Rate		3.37%
Number of Communities Encumbered | community		12
Fixed Rate Debt | Weighted Average
Secured debt instruments
Years to maturity		7 years
Variable Rate Debt
Secured debt instruments
Principal outstanding		$ 26,935		26,932
Weighted Average Interest Rate		0.77%
Number of Communities Encumbered | community		1
Variable Rate Debt | Weighted Average
Secured debt instruments
Years to maturity		11 years
Commercial Paper
Secured debt instruments
Weighted Average Interest Rate		0.26%
Borrowings outstanding at end of period		$ 210,000		190,000
Borrowings outstanding		$ 210,000		190,000
Commercial Paper | Weighted Average
Secured debt instruments
Years to maturity		1 month 6 days
Mortgages Note Payable | Fixed Rate Debt
Secured debt instruments
Principal outstanding		$ 876,080		824,550
Weighted Average Interest Rate		3.37%
Number of Communities Encumbered | community		12
Mortgages Note Payable | Fixed Rate Debt | Weighted Average
Secured debt instruments
Years to maturity		7 years
Tax-exempt secured notes payable | Variable Rate Debt
Secured debt instruments
Principal outstanding		$ 27,000		27,000
Weighted Average Interest Rate		0.77%
Number of Communities Encumbered | community		1
Tax-exempt secured notes payable | Variable Rate Debt | Weighted Average
Secured debt instruments
Years to maturity		11 years
Secured Debt
Secured debt instruments
Principal outstanding		$ 919,177		862,147
Weighted Average Interest Rate		3.29%
Total Debt, net		$ 919,177
Number of Communities Encumbered | community		13
Secured Debt | Weighted Average
Secured debt instruments
Years to maturity		7 years 1 month 6 days
Secured Debt | Fixed Rate Debt
Secured debt instruments
Total Debt, net		$ 892,242
Deferred financing costs and other non-cash adjustments		(16,162)		(10,665)
Secured Debt | Variable Rate Debt
Secured debt instruments
Total Debt, net		26,935
Deferred finance costs, net		$ (65)		(68)
Unsecured Revolving credit facility due 2023 | Weighted Average
Secured debt instruments
Years to maturity		1 year 9 months 18 days
Unsecured Working Capital Credit Facility
Secured debt instruments
Weighted Average Interest Rate		0.94%
Borrowings outstanding		$ 17,813		28,024
Unsecured Working Capital Credit Facility | Weighted Average
Secured debt instruments
Years to maturity		9 months 18 days
Term Loan due September 2023
Secured debt instruments
Weighted Average Interest Rate		1.02%
Senior Notes		$ 35,000		35,000
Term Loan due September 2023 | Weighted Average
Secured debt instruments
Years to maturity		2 years 6 months
Term Loan due September 2023 | Fixed Rate Debt
Secured debt instruments
Weighted Average Interest Rate		1.07%
Senior Notes		$ 315,000		$ 315,000
Term Loan due September 2023 | Fixed Rate Debt | Weighted Average
Secured debt instruments
Years to maturity		2 years 6 months
8.50% Debentures, Due September 2024
Secured debt instruments
Interest rate		8.50%		8.50%
Weighted Average Interest Rate		8.50%
Senior Notes		$ 15,644		$ 15,644
8.50% Debentures, Due September 2024 | Weighted Average
Secured debt instruments
Years to maturity		3 years 6 months
4.00% Medium-Term Note due October 2025
Secured debt instruments
Interest rate		4.00%	4.00%	4.00%
Unamortized discount		$ 0		$ 327
Senior Notes				$ 299,673
2.95% Medium-Term Note due September 2026
Secured debt instruments
Interest rate		2.95%		2.95%
Weighted Average Interest Rate		2.89%
Senior Notes		$ 300,000		$ 300,000
2.95% Medium-Term Note due September 2026 | Weighted Average
Secured debt instruments
Years to maturity		5 years 4 months 24 days
3.50 Medium-Term Note due July 2027
Secured debt instruments
Interest rate		3.50%		3.50%
Unamortized discount		$ 441		$ 458
Weighted Average Interest Rate		4.03%
Senior Notes		$ 299,559		$ 299,542
3.50 Medium-Term Note due July 2027 | Weighted Average
Secured debt instruments
Years to maturity		6 years 3 months 18 days
3.50% Medium-Term Notes Due January 2028
Secured debt instruments
Interest rate		3.50%		3.50%
Unamortized discount		$ 806		$ 835
Weighted Average Interest Rate		3.50%
Senior Notes		$ 299,194		$ 299,165
3.50% Medium-Term Notes Due January 2028 | Weighted Average
Secured debt instruments
Years to maturity		6 years 9 months 18 days
4.40% Medium-Term Notes due January 2029
Secured debt instruments
Principal outstanding					$ 300,000
Interest rate		4.40%		4.40%
Unamortized discount		$ 5		$ 5
Weighted Average Interest Rate		4.27%
Senior Notes		$ 299,995		$ 299,995
4.40% Medium-Term Notes due January 2029 | Weighted Average
Secured debt instruments
Years to maturity		7 years 9 months 18 days
3.20% Medium-Term Notes due January 2030
Secured debt instruments
Interest rate		3.20%		3.20%
Unamortized discount		$ 12,070		$ 12,412
Weighted Average Interest Rate	3.32%	3.32%
Senior Notes		$ 612,070		$ 612,412
3.20% Medium-Term Notes due January 2030 | Weighted Average
Secured debt instruments
Years to maturity		8 years 9 months 18 days
3.00% Medium-Term Notes due August 2031
Secured debt instruments
Interest rate		3.00%		3.00%
Unamortized discount		$ 1,003		$ 1,027
Weighted Average Interest Rate		3.01%
Senior Notes		$ 398,997		398,973
3.00% Medium-Term Notes due August 2031 | Weighted Average
Secured debt instruments
Years to maturity		10 years 4 months 24 days
2.10% Medium Term Note Due August 1, 2032
Secured debt instruments
Interest rate		2.10%
Unamortized discount		$ 399		408
Weighted Average Interest Rate		2.10%
Senior Notes		$ 399,601		$ 399,592
2.10% Medium Term Note Due August 1, 2032 | Weighted Average
Secured debt instruments
Years to maturity		11 years 3 months 18 days
1.90% Medium-Term Notes due March 2033
Secured debt instruments
Interest rate		1.90%		1.90%
Unamortized discount		$ 1,440		$ 1,471
Weighted Average Interest Rate		1.90%
Senior Notes		$ 348,560		$ 348,529
1.90% Medium-Term Notes due March 2033 | Weighted Average
Secured debt instruments
Years to maturity		12 years
2.10% Senior Unsecured Medium-Term Note due 2033
Secured debt instruments
Interest rate		2.10%	2.10%	2.10%
Unamortized discount		$ 1,215		$ 0
Weighted Average Interest Rate		2.10%
Senior Notes		$ 298,785
2.10% Senior Unsecured Medium-Term Note due 2033 | Weighted Average
Secured debt instruments
Years to maturity		12 years 2 months 12 days
3.10% Medium-Term Notes due November 2034
Secured debt instruments
Interest rate		3.10%		3.10%
Unamortized discount		$ 1,199		$ 1,221
Weighted Average Interest Rate		3.13%
Senior Notes		$ 298,801		298,779
3.10% Medium-Term Notes due November 2034 | Weighted Average
Secured debt instruments
Years to maturity		13 years 7 months 6 days
Other
Secured debt instruments
Senior Notes		$ 9		10
Unsecured Debt
Secured debt instruments
Weighted Average Interest Rate		2.72%
Total Debt, net		$ 4,121,998
Total Unsecured Debt, net		4,121,998		4,114,401
Deferred finance costs, net		$ (27,030)		$ (25,937)
Unsecured Debt | Weighted Average
Secured debt instruments
Years to maturity		8 years 4 months 24 days

SECURED AND UNSECURED DEBT, N_4

SECURED AND UNSECURED DEBT, NET - Variable Rate Debt (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
SECURED AND UNSECURED DEBT, NET
Unamortized net premium	$ 18.9	$ 12.9
Secured credit facilities
Borrowings outstanding at end of period	$ 2.3	$ 2.8

SECURED AND UNSECURED DEBT, N_5

SECURED AND UNSECURED DEBT, NET - Credit Facilities (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended	12 Months Ended
	Feb. 28, 2021	Mar. 31, 2021	Dec. 31, 2020
Summary of short-term bank borrowings under unsecured commercial bank credit facility
Borrowings outstanding at end of year		$ 2,300	$ 2,800
Unsecured Commercial Bank Credit Facility
Summary of short-term bank borrowings under unsecured commercial bank credit facility
Total revolving credit facility		2,000,000
Unsecured Revolving credit facility due 2023 | Unsecured Commercial Bank Credit Facility
Summary of short-term bank borrowings under unsecured commercial bank credit facility
Total revolving credit facility		1,100,000
Term Loan due September 2023 | Unsecured Commercial Bank Credit Facility
Summary of short-term bank borrowings under unsecured commercial bank credit facility
Total revolving credit facility		350,000
4.00% Medium-Term Note due October 2025
Summary of short-term bank borrowings under unsecured commercial bank credit facility
Repayments of outstanding borrowing	$ 300,000
Revolving Credit Facility | Unsecured Commercial Bank Credit Facility
Summary of short-term bank borrowings under unsecured commercial bank credit facility
Total revolving credit facility		1,100,000	1,100,000
Weighted average daily borrowings during the year ended			42,186
Maximum daily borrowings during the year ended			$ 375,000
Weighted average interest rate during the year ended			1.40%
Unsecured Working Capital Credit Facility
Summary of short-term bank borrowings under unsecured commercial bank credit facility
Total revolving credit facility		75,000	$ 75,000
Borrowings outstanding at end of year		17,813	28,024
Weighted average daily borrowings during the year ended		7,438	20,132
Maximum daily borrowings during the year ended		$ 37,560	$ 54,974
Weighted average interest rate during the year ended		0.90%	1.40%
Interest rate at end of the period		0.90%	1.00%

SECURED AND UNSECURED DEBT, N_6

SECURED AND UNSECURED DEBT, NET - Short Term Debt (Details) - Commercial Paper - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Unsecured Debt
Total unsecured commercial paper program	$ 500,000	$ 500,000
Borrowings outstanding at end of period	210,000	190,000
Weighted average daily borrowings during the period ended	191,389	227,090
Maximum daily borrowings during the period ended	$ 340,000	$ 500,000
Weighted average interest rate during the period ended	0.30%	0.90%
Interest rate at end of the period	0.30%	0.30%
Commercial paper	$ 210,000	$ 190,000

SECURED AND UNSECURED DEBT, N_7

SECURED AND UNSECURED DEBT, NET - Unsecured Maturities (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Aggregate maturities of unsecured debt
2021	$ 210,827
2022	18,953
2023	351,183
2024	111,672
2025	174,043
2026	351,963
2027	302,045
2028	423,435
2029	491,986
2030	672,500
Thereafter	1,937,930
Subtotal	5,046,537
Non-cash	(5,362)
Total	5,041,175	$ 4,976,548
Secured Debt
Aggregate maturities of unsecured debt
2021	827
2022	1,140
2023	1,183
2024	96,028
2025	174,043
2026	51,963
2027	2,045
2028	123,435
2029	191,986
2030	72,500
Thereafter	187,930
Subtotal	903,080
Non-cash	16,097
Total	919,177
Unsecured Debt
Aggregate maturities of unsecured debt
2021	210,000
2022	17,813
2023	350,000
2024	15,644
2025	0
2026	300,000
2027	300,000
2028	300,000
2029	300,000
2030	600,000
Thereafter	1,750,000
Subtotal	4,143,457
Non-cash	(21,459)
Total	4,121,998
Fixed Rate Debt | Secured Debt
Aggregate maturities of unsecured debt
2021	827
2022	1,140
2023	1,183
2024	96,028
2025	174,043
2026	51,963
2027	2,045
2028	123,435
2029	191,986
2030	72,500
Thereafter	160,930
Subtotal	876,080
Non-cash	16,162
Total	892,242
Variable Rate Debt | Secured Debt
Aggregate maturities of unsecured debt
Thereafter	27,000
Subtotal	27,000
Non-cash	(65)
Total	$ 26,935

SECURED AND UNSECURED DEBT, N_8

SECURED AND UNSECURED DEBT, NET - Debt Covenants (Details) $ in Thousands	1 Months Ended		3 Months Ended
	Feb. 28, 2021USD ($)	Feb. 29, 2020	Mar. 31, 2021USD ($)loan	Mar. 31, 2020USD ($)	Jan. 31, 2021USD ($)	Dec. 31, 2020USD ($)	Jul. 31, 2020USD ($)
Fixed and variable rate debt
Amortization of financing costs			$ 1,200	$ 1,000
Secured Debt
Secured debt amount which encumbers real estate owned based upon book value			$ 1,500,000
Percentage of secured debt which encumbers real estate owned based upon book value			11.20%
Secured debt amount of real estate owned which is unencumbered			$ 11,600,000
Percentage of secured debt of real estate owned which is unencumbered			88.80%
Interest rate at end of the period			2.84%
Long-term Debt			$ 5,046,537
Extinguishment of debt costs			40,769
Unamortized net premium			$ 18,900			$ 12,900
Weighted Average Interest Rate			2.84%
300 Home Operating Community in Franklin
Secured Debt
Long-term Debt					$ 51,800
Unamortized net premium					6,600
Fixed Rate Debt
Secured Debt
Principal outstanding			$ 892,242			835,215
Interest rate at end of the period			3.37%
Weighted Average Interest Rate			3.37%
Fixed Rate Debt | 300 Home Operating Community in Franklin
Secured Debt
Long-term Debt					51,800
Long term debt fair value					$ 58,400
Interest rate					4.39%
Variable Rate Debt
Secured Debt
Principal outstanding			$ 26,935			26,932
Interest rate at end of the period			0.77%
Weighted Average Interest Rate			0.77%
Commercial Paper
Secured Debt
Interest rate at end of the period			0.26%
Weighted Average Interest Rate			0.26%
Unsecured Debt
Secured Debt
Interest rate at end of the period			2.72%
Long-term Debt			$ 4,143,457
Credit facility interest rate			90
Basis points added to to variable rate			90.00%
Weighted Average Interest Rate			2.72%
Unsecured Debt | Maximum
Secured Debt
Basis points added to to variable rate			165.00%
Unsecured Debt | Minimum
Secured Debt
Basis points added to to variable rate			80.00%
Unsecured Working Capital Credit Facility
Secured Debt
Credit facilities with aggregate commitment			$ 75,000			$ 75,000
Interest rate at end of the period			0.94%
Credit facility interest rate			82.5
Weighted Average Interest Rate			0.94%
Unsecured Working Capital Credit Facility | Maximum
Secured Debt
Basis points added to to variable rate			145.00%
Unsecured Working Capital Credit Facility | Minimum
Secured Debt
Basis points added to to variable rate			75.00%
3.50 Medium-Term Note due July 2027
Secured Debt
Interest rate at end of the period			4.03%
Interest rate			3.50%			3.50%
Portion of medium term note subject to interest rate swaps			$ 200,000
Weighted average interest rate (as a percent)			4.03%
Senior Notes			$ 299,559			$ 299,542
Weighted Average Interest Rate			4.03%
2.10% Medium Term Note Due August 1, 2032
Secured Debt
Interest rate at end of the period			2.10%
Interest rate			2.10%
Senior Notes			$ 399,601			399,592
Weighted Average Interest Rate			2.10%
Mortgages Note Payable | Fixed Rate Debt
Secured Debt
Principal outstanding			$ 876,080			824,550
Interest rate at end of the period			3.37%
Weighted Average Interest Rate			3.37%
Debt Assumed As Part of Acquisition
Secured Debt
Amortization of debt discount (Premium)			$ 700	$ 2,600
Tax-exempt secured notes payable | Variable Rate Debt
Secured Debt
Principal outstanding			$ 27,000			27,000
Interest rate at end of the period			0.77%
Weighted Average Interest Rate			0.77%
Tax-exempt secured notes payable | Variable Rate Debt
Secured Debt
Notes payable maximum interest rates range			0.77%
Revolving Credit Facility
Secured Debt
Basis points added to to variable rate			82.50%
Commitment fee			15.00%
Revolving Credit Facility | Maximum
Secured Debt
Basis points added to to variable rate			145.00%
Commitment fee			30.00%
Revolving Credit Facility | Minimum
Secured Debt
Basis points added to to variable rate			75.00%
Commitment fee			10.00%
Term Loan due September 2023
Secured Debt
Interest rate at end of the period			1.02%
Long-term Debt, Weighted Average Interest Rate			1.07%
Senior Notes			$ 35,000			35,000
Weighted Average Interest Rate			1.02%
Term Loan due September 2023 | Fixed Rate Debt
Secured Debt
Interest rate at end of the period			1.07%
Senior Notes			$ 315,000			$ 315,000
Weighted Average Interest Rate			1.07%
4.00% Medium-Term Note due October 2025
Secured Debt
Repayments of outstanding borrowing	$ 300,000
Interest rate	4.00%		4.00%			4.00%
Senior Notes						$ 299,673
4.00% Medium-Term Note due October 2025 | Interest expense
Secured Debt
Extinguishment of debt costs	$ 42,000
4.40% Medium-Term Notes due January 2029
Secured Debt
Principal outstanding							$ 300,000
Interest rate at end of the period			4.27%
Interest rate			4.40%			4.40%
Portion of medium term note subject to interest rate swaps			$ 150,000
Long-term Debt, Weighted Average Interest Rate			4.27%
Senior Notes			$ 299,995			$ 299,995
Weighted Average Interest Rate			4.27%
2.95% Medium-Term Note due September 2026
Secured Debt
Interest rate at end of the period			2.89%
Interest rate			2.95%			2.95%
Portion of medium term note subject to interest rate swaps			$ 100,000
Long-term Debt, Weighted Average Interest Rate			2.89%
Senior Notes			$ 300,000			$ 300,000
Weighted Average Interest Rate			2.89%
3.20% Medium-Term Notes due January 2030
Secured Debt
Interest rate at end of the period		3.32%	3.32%
Interest rate			3.20%			3.20%
Senior Notes			$ 612,070			$ 612,412
Weighted Average Interest Rate		3.32%	3.32%
3.00% Medium-Term Notes due August 2031
Secured Debt
Interest rate at end of the period			3.01%
Interest rate			3.00%			3.00%
Senior Notes			$ 398,997			$ 398,973
Weighted Average Interest Rate			3.01%
Medium-Term Notes Due August 2031
Secured Debt
Debt			$ 150,000
Medium-Term Notes Due August 2031 | Weighted Average
Secured Debt
Interest rate at end of the period			3.01%
Weighted Average Interest Rate			3.01%
3.10% senior unsecured notes due 2034 | Weighted Average
Secured Debt
Interest rate at end of the period			3.13%
Weighted Average Interest Rate			3.13%
2.10% Senior Unsecured Medium-Term Note due 2033
Secured Debt
Interest rate at end of the period			2.10%
Interest rate	2.10%		2.10%			2.10%
Medium-term notes	$ 300,000
Percentage of principal amount at issuance	99.592
Senior Notes			$ 298,785
Weighted Average Interest Rate			2.10%
Unsecured Commercial Bank Credit Facility
Secured Debt
Credit facilities with aggregate commitment			$ 2,000,000
Unsecured Commercial Bank Credit Facility | Unsecured Revolving credit facility due 2023
Secured Debt
Credit facilities with aggregate commitment			$ 1,100,000
Number of Extensions of loan | loan			2
Extension period of option on loan			6 months
Unsecured Commercial Bank Credit Facility | Revolving Credit Facility
Secured Debt
Credit facilities with aggregate commitment			$ 1,100,000			$ 1,100,000
Unsecured Commercial Bank Credit Facility | Term Loan due September 2023
Secured Debt
Credit facilities with aggregate commitment			$ 350,000
Mortgages Note Payable | Fixed Rate Debt | Maximum
Secured Debt
Notes payable maximum interest rates range			4.39%
Mortgages Note Payable | Fixed Rate Debt | Minimum
Secured Debt
Notes payable maximum interest rates range			2.62%
Mortgages Note Payable | Fair Value, Measurements, Recurring | Carrying Amount | Mortgages Note Payable | Fixed Rate Debt
Secured Debt
Principal outstanding			$ 894,967			$ 837,473

INCOME_(LOSS) PER SHARE (Detail

INCOME/(LOSS) PER SHARE (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020	Jul. 31, 2017
Antidilutive securities
Net income/(loss)		$ 3,274	$ 5,540
Net (income)/loss attributable to redeemable noncontrolling interests in the Operating Partnership and DownREIT Partnership		(154)	(313)
Net (income)/loss attributable to noncontrolling interests		(16)	(6)
Net income/(loss) attributable to UDR, Inc.		3,104	5,221
Distributions to preferred stockholders - Series E (Convertible)		(1,056)	(1,066)
Net income/(loss) attributable to common stockholders		$ 2,048	$ 4,155
Denominator for income/(loss) per share:
Weighted average common shares outstanding		296,800,000	294,731,000
Non-vested restricted stock awards		(263,000)	(274,000)
Denominator for basic income/(loss) per share		296,537,000	294,457,000
Incremental shares issuable from assumed conversion of unvested LTIP Units and unvested restricted stock		489,000	703,000
Denominator for diluted income/(loss) per share		297,026,000	295,160,000
Income/(loss) per weighted average common share - basic		$ 0.01	$ 0.01
Income/(loss) per weighted average common share - diluted		$ 0.01	$ 0.01
Number of shares authorized	350,000,000	350,000,000		350,000,000
OP/DownREIT Units
Antidilutive securities
Antidilutive securities		22,398,000	22,228,000
Convertible preferred stock
Antidilutive securities
Antidilutive securities		2,918,000	3,011,000
Unvested LTIP Units and unvested restricted stock
Antidilutive securities
Antidilutive securities		489,000	703,000
ATM
Denominator for income/(loss) per share:
Number of shares authorized					20,000,000
Shares of common stock available for future issuance	9,600,000	9,600,000
Forward Sales Agreement
Denominator for income/(loss) per share:
Number of shares authorized	2,300,000	2,300,000
Number of shares sold	0
Weighted average price per share		$ 43.85
Forward price	$ 43.51
Shares of common stock available for future issuance	7,000,000	7,000,000
Shares settled		0

NONCONTROLLING INTERESTS (Detai

NONCONTROLLING INTERESTS (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Redeemable noncontrolling interests in the Operating Partnership
Minimum holding period prior to redemption (in years)	1 year
Redeemable noncontrolling interests in the Operating Partnership and DownREIT Partnership, beginning of year	$ 856,294
Mark-to-market adjustment to redeemable noncontrolling interests in the Operating Partnership and DownREIT Partnership	131,700	$ (205,713)
Conversion of OP Units/DownREIT Units to Common Stock	(4,497)
Net income/(loss) attributable o redeemable noncontrolling interests in the Operating Partnership and DownREIT Partnership	154	313
Distributions to redeemable noncontrolling interests in the Operating Partnership and DownREIT Partnership	(8,586)
Vesting of Long-Term Incentive Plan Units	14,578
Allocation of other comprehensive income/(loss)	43
Redeemable noncontrolling interests in the Operating Partnership and DownREIT Partnership, end of year	989,686
Net income/(loss) attributable to noncontrolling interests	8	(10)
Maximum
Redeemable noncontrolling interests in the Operating Partnership
Net income/(loss) attributable to noncontrolling interests	$ (100)	$ (100)
LTIP Units | Minimum
Redeemable noncontrolling interests in the Operating Partnership
Vesting period	1 year
LTIP Units | Maximum
Redeemable noncontrolling interests in the Operating Partnership
Vesting period	3 years

FAIR VALUE OF DERIVATIVES AND_3

FAIR VALUE OF DERIVATIVES AND FINANCIAL INSTRUMENTS (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Fair Value
Notes receivable, net	$ 155,206	$ 157,992
Unsecured debt instruments
Redeemable noncontrolling interests in the Operating Partnership and DownREIT Partnership	989,686	856,294
Transfer Between the Levels	0
Carrying Amount | Fair Value, Measurements, Recurring
Fair Value
Notes receivable, net	155,206	157,992
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis
Total assets	155,215	157,994
Unsecured debt instruments
Total liabilities	5,071,062	5,004,978
Redeemable noncontrolling interests in the Operating Partnership and DownREIT Partnership	989,686	856,294
Carrying Amount | Interest rate contracts | Fair Value, Measurements, Recurring
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis
Derivative Asset Designated as Hedging Instrument, Fair Value	9	2
Derivatives - Interest rate contracts	67	167
Carrying Amount | Credit facilities | Fair Value, Measurements, Recurring
Unsecured debt instruments
Unsecured debt instruments	17,813	28,024
Carrying Amount | Commercial bank | Fair Value, Measurements, Recurring
Unsecured debt instruments
Commercial paper	210,000	190,000
Carrying Amount | Senior Unsecured Notes | Fair Value, Measurements, Recurring
Unsecured debt instruments
Unsecured debt instruments	3,921,215	3,922,314
Fair Value | Fair Value, Measurements, Recurring
Fair Value
Notes receivable, net	169,001	170,411
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis
Total assets	169,010	170,413
Unsecured debt instruments
Total liabilities	5,136,738	5,382,320
Redeemable noncontrolling interests in the Operating Partnership and DownREIT Partnership	989,686	856,294
Fair Value | Interest rate contracts | Fair Value, Measurements, Recurring
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis
Derivative Asset Designated as Hedging Instrument, Fair Value	9	2
Derivatives - Interest rate contracts	67	167
Fair Value | Credit facilities | Fair Value, Measurements, Recurring
Unsecured debt instruments
Unsecured debt instruments	17,813	28,024
Fair Value | Commercial bank | Fair Value, Measurements, Recurring
Unsecured debt instruments
Commercial paper	210,000	190,000
Fair Value | Senior Unsecured Notes | Fair Value, Measurements, Recurring
Unsecured debt instruments
Unsecured debt instruments	3,983,183	4,283,045
Fair Value | Level 2 | Fair Value, Measurements, Recurring
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis
Total assets	9	2
Unsecured debt instruments
Total liabilities	67	167
Redeemable noncontrolling interests in the Operating Partnership and DownREIT Partnership	989,686	856,294
Fair Value | Level 2 | Interest rate contracts | Fair Value, Measurements, Recurring
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis
Derivative Asset Designated as Hedging Instrument, Fair Value	9	2
Derivatives - Interest rate contracts	67	167
Fair Value | Level 3 | Fair Value, Measurements, Recurring
Fair Value
Notes receivable, net	169,001	170,411
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis
Total assets	169,001	170,411
Unsecured debt instruments
Total liabilities	5,136,671	5,382,153
Fair Value | Level 3 | Credit facilities | Fair Value, Measurements, Recurring
Unsecured debt instruments
Unsecured debt instruments	17,813	28,024
Fair Value | Level 3 | Commercial bank | Fair Value, Measurements, Recurring
Unsecured debt instruments
Commercial paper	210,000	190,000
Fair Value | Level 3 | Senior Unsecured Notes | Fair Value, Measurements, Recurring
Unsecured debt instruments
Unsecured debt instruments	3,983,183	4,283,045
Fixed Rate Debt
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis
Secured debt including debt on real estate held for sale	892,242	835,215
Variable Rate Debt
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis
Secured debt including debt on real estate held for sale	26,935	26,932
Tax-exempt secured notes payable | Variable Rate Debt
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis
Secured debt including debt on real estate held for sale	27,000	27,000
Tax-exempt secured notes payable | Variable Rate Debt | Carrying Amount | Tax-exempt secured notes payable | Fair Value, Measurements, Recurring
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis
Secured debt including debt on real estate held for sale	27,000	27,000
Tax-exempt secured notes payable | Variable Rate Debt | Fair Value | Tax-exempt secured notes payable | Fair Value, Measurements, Recurring
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis
Secured debt including debt on real estate held for sale	27,000	27,000
Tax-exempt secured notes payable | Variable Rate Debt | Fair Value | Level 3 | Tax-exempt secured notes payable | Fair Value, Measurements, Recurring
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis
Secured debt including debt on real estate held for sale	27,000	27,000
Mortgages Note Payable | Fixed Rate Debt
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis
Secured debt including debt on real estate held for sale	876,080	824,550
Mortgages Note Payable | Fixed Rate Debt | Carrying Amount | Mortgages Note Payable | Fair Value, Measurements, Recurring
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis
Secured debt including debt on real estate held for sale	894,967	837,473
Mortgages Note Payable | Fixed Rate Debt | Fair Value | Mortgages Note Payable | Fair Value, Measurements, Recurring
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis
Secured debt including debt on real estate held for sale	898,675	854,084
Mortgages Note Payable | Fixed Rate Debt | Fair Value | Level 3 | Mortgages Note Payable | Fair Value, Measurements, Recurring
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis
Secured debt including debt on real estate held for sale	$ 898,675	$ 854,084

DERIVATIVES AND HEDGING ACTIV_3

DERIVATIVES AND HEDGING ACTIVITY - Interest Rate Derivatives (Details) $ in Thousands	Mar. 31, 2021USD ($)instrument
Derivatives
Estimated additional accumulated other comprehensive Income/(Loss) transferred to interest expense	$ 1,600
Unsecured Commercial Bank Credit Facility
Derivatives
Total revolving credit facility	$ 2,000,000
Designated as Hedging Instrument | Interest rate swap and caps
Derivatives
Number of Interest Rate Derivatives Held | instrument	4
Notional	$ 334,880
Not Designated as Hedging Instrument
Derivatives
Notional	$ 0

DERIVATIVES AND HEDGING ACTIV_4

DERIVATIVES AND HEDGING ACTIVITY - Undesignated Interest Rate Derivatives (Details) - Interest rate contracts - Designated as Hedging Instrument - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Other assets
Fair value of Company's derivative financial instruments and their classification on Consolidated Balance Sheet
Derivative Asset Designated as Hedging Instrument, Fair Value	$ 9	$ 2
Other liabilities
Fair value of Company's derivative financial instruments and their classification on Consolidated Balance Sheet
Gross Amounts of Recognized Liabilities	$ 67	$ 167

DERIVATIVES AND HEDGING ACTIV_5

DERIVATIVES AND HEDGING ACTIVITY - Fair Value (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Effect of derivative instruments on the Consolidated Statements of Operations
Unrealized holding gain/(loss)	$ 127	$ (2,917)
Interest rate contracts | Interest expense | Cash Flow Hedging
Effect of derivative instruments on the Consolidated Statements of Operations
Unrealized holding gain/(loss)	127	(2,917)
Gain/(Loss) reclassified from Accumulated OCI in Interest Expense	$ (446)	$ (357)

DERIVATIVES AND HEDGING ACTIV_6

DERIVATIVES AND HEDGING ACTIVITY - Effectiveness (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Derivatives and hedging activity
Total amount of Interest expense presented on the Consolidated Statements of Operations	$ 78,156	$ 39,317

DERIVATIVES AND HEDGING ACTIV_7

DERIVATIVES AND HEDGING ACTIVITY - Offsetting Assets and Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Offsetting derivative assets
Net Amounts of Assets Presented in the Consolidated Balance Sheets (a)	$ 9	$ 2
Net Amount	9	2
Offsetting derivative liabilities
Net Amounts of Liabilities Presented in the Consolidated Balance Sheets (a)	67	167
Net Amount	$ 67	$ 167

STOCK BASED COMPENSATION (Detai

STOCK BASED COMPENSATION (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
General and administrative expense
Stock based compensation
Stock based compensation expense	$ 4.9	$ 6.8

COMMITMENTS AND CONTINGENCIES_2

COMMITMENTS AND CONTINGENCIES (Details) $ in Thousands	Apr. 28, 2021USD ($)home	Mar. 31, 2021USD ($)community
Real estate properties
Number of communities owned (in communities) | community		150
Costs Incurred to Date		$ 275,107
UDR's Remaining Commitment		301,404
Real estate technology investments RETV I
Real estate properties
Costs Incurred to Date		22,641
UDR's Remaining Commitment		5,220
Real estate technology investments RETV II
Real estate properties
Costs Incurred to Date		2,184
UDR's Remaining Commitment		$ 14,025
Wholly owned - under development
Real estate properties
Number of communities owned (in communities) | community		5
Costs Incurred to Date		$ 243,200
UDR's Remaining Commitment		$ 258,300
Preferred Equity Investments
Real estate properties
Number of communities owned (in communities) | community		2
Costs Incurred to Date		$ 7,082
UDR's Remaining Commitment		$ 43,104
945 Apartment homes operating community in Frisco, Texas
Real estate properties
Number of apartment homes | home	945
Contractual purchase price commitment	$ 167,000
Deposit on purchase	$ 7,500

REPORTABLE SEGMENTS (Details)

REPORTABLE SEGMENTS (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2021USD ($)homesegment	Mar. 31, 2020USD ($)home	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)
Segments
Same store communities | home	45,403	45,403
Reportable Segments
Number of reportable segments | segment	2
Condition for Community considered to have stabilized occupancy	90%
Time to maintain percent occupancy to be considered a community	3 months
Practical expedient, single lease component	true
Summary of rental income and NOI for UDRs reportable segments and reconciliation of NOI to loss from continuing operations
Rental income	$ 299,826	$ 320,093
Reconciling items:
Joint venture management and other fees	$ 1,615	$ 1,388
Type of revenue	udr:ManagementAndOtherFeesMember	udr:ManagementAndOtherFeesMember
Property management	$ (8,995)	$ (9,203)
Other operating expenses	(4,435)	(4,966)
Real estate depreciation and amortization	(144,088)	(155,476)
General and administrative	(12,736)	(14,978)
Casualty-related (charges)/recoveries, net	(5,577)	(1,251)
Other depreciation and amortization	(2,601)	(2,025)
Gain/(loss) on sale of property	50,829
Income/(loss) from unconsolidated entities	4,922	3,367
Interest expense	(78,156)	(39,317)
Interest income and other income/(expense), net	2,057	2,700
Tax (provision)/benefit, net	(619)	(164)
Net (income)/loss attributable to redeemable noncontrolling interests in the Operating Partnership and DownREIT Partnership	(154)	(313)
Net (income)/loss attributable to noncontrolling interests	(16)	(6)
Net income/(loss) attributable to UDR, Inc.	3,104	5,221
Reportable apartment home segment assets:
Total segment assets	13,095,900		$ 13,071,472
Accumulated depreciation	(4,730,021)		(4,605,366)
Total real estate owned, net of accumulated depreciation	8,365,879		8,466,106
Reconciling items:
Cash and cash equivalents	1,172	980	1,409	$ 8,106
Restricted cash	33,428	21,949	22,762	$ 25,185
Notes receivable, net	155,206		157,992
Investment in and advances to unconsolidated joint ventures, net	620,111		600,233
Operating lease right-of-use assets	200,064		200,913
Other assets	190,696		188,118
Total consolidated assets	9,566,556		9,637,533
Same Store Communities West Region
Summary of rental income and NOI for UDRs reportable segments and reconciliation of NOI to loss from continuing operations
Lease revenue	100,170	111,215
Other revenue	2,718	2,930
Rental income	102,888	114,145
Reportable apartment home segment NOI	74,845	86,091
Reportable apartment home segment assets:
Total segment assets	4,255,427		4,247,900
Same Store Communities Mid-Atlantic Region
Summary of rental income and NOI for UDRs reportable segments and reconciliation of NOI to loss from continuing operations
Lease revenue	59,917	62,537
Other revenue	1,702	1,701
Rental income	61,619	64,238
Reportable apartment home segment NOI	42,402	45,317
Reportable apartment home segment assets:
Total segment assets	2,703,939		2,698,049
Same Store Communities Northeast Region
Summary of rental income and NOI for UDRs reportable segments and reconciliation of NOI to loss from continuing operations
Lease revenue	52,050	57,495
Other revenue	1,047	1,064
Rental income	53,097	58,559
Reportable apartment home segment NOI	33,343	40,323
Reportable apartment home segment assets:
Total segment assets	2,904,450		2,900,017
Same Store Communities Southeast Region
Summary of rental income and NOI for UDRs reportable segments and reconciliation of NOI to loss from continuing operations
Lease revenue	34,637	33,781
Other revenue	1,493	1,524
Rental income	36,130	35,305
Reportable apartment home segment NOI	24,317	24,537
Reportable apartment home segment assets:
Total segment assets	978,568		974,754
Same Store Communities Southwest Region
Summary of rental income and NOI for UDRs reportable segments and reconciliation of NOI to loss from continuing operations
Lease revenue	23,211	23,815
Other revenue	875	820
Rental income	24,086	24,635
Reportable apartment home segment NOI	14,834	15,383
Reportable apartment home segment assets:
Total segment assets	896,728		897,505
Non-Mature communities/Other
Summary of rental income and NOI for UDRs reportable segments and reconciliation of NOI to loss from continuing operations
Lease revenue	21,460	22,779
Other revenue	546	432
Rental income	22,006	23,211
Reportable apartment home segment NOI	11,317	13,814
Reportable apartment home segment assets:
Total segment assets	1,356,788		$ 1,353,247
Total Communities
Summary of rental income and NOI for UDRs reportable segments and reconciliation of NOI to loss from continuing operations
Lease revenue	291,445	311,622
Other revenue	8,381	8,471
Rental income	299,826	320,093
Reportable apartment home segment NOI	$ 201,058	$ 225,465
Taxable REIT Subsidiaries
Reportable Segments
Management fee (as a percent)	3.00%