UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM N-CSRS CERTIFIED SHAREHOLDER REPORT OF REGISTERED MANAGEMENT INVESTMENT COMPANIES Investment Company Act file number 811-04802 Name of Fund: BlackRock Intermediate Municipal Fund of BlackRock Municipal Series Trust Fund Address: P.O. Box 9011 Princeton, NJ 08543-9011 Name and address of agent for service: Robert C. Doll, Jr., Chief Executive Officer, BlackRock Intermediate Municipal Fund of BlackRock Municipal Series Trust, 800 Scudders Mill Road, Plainsboro, NJ, 08536. Mailing address: P.O. Box 9011, Princeton, NJ, 08543-9011 Registrant's telephone number, including area code: (800) 441-7762 Date of fiscal year end: 10/31/07 Date of reporting period: 11/01/06 - 04/30/07 Item 1 - Report to Stockholders ALTERNATIVES BLACKROCK SOLUTIONS EQUITIES FIXED INCOME LIQUIDITY REAL ESTATE BlackRock Intermediate BLACKROCK Municipal Fund OF BLACKROCK MUNICIPAL SERIES TRUST SEMI-ANNUAL REPORT APRIL 30, 2007 | (UNAUDITED) NOT FDIC INSURED MAY LOSE VALUE NO BANK GUARANTEE BlackRock Intermediate Municipal Fund Portfolio Information as of April 30, 2007 Quality Ratings by Percent of S&P/Moody's Total Investments - -------------------------------------------------------------------------------- AAA/Aaa ...................................................... 69.1% AA/Aa ........................................................ 9.5 A/A .......................................................... 2.9 BBB/Baa ...................................................... 9.0 BB/Ba ........................................................ 0.6 NR (Not Rated) ............................................... 3.7 Other* ....................................................... 5.2 - -------------------------------------------------------------------------------- * Includes portfolio holdings in mutual funds, variable rate demand notes and short-term investments. Percent of Distribution by Market Sector Total Investments - -------------------------------------------------------------------------------- Other Revenue Bonds .......................................... 65.3% General Obligation Bonds ..................................... 29.5 Other* ....................................................... 5.2 - -------------------------------------------------------------------------------- * Includes portfolio holdings in mutual funds, variable rate demand notes and short-term investments. Officers and Trustees Robert C. Doll, Jr., Fund President and Trustee Ronald W. Forbes, Trustee Cynthia A. Montgomery, Trustee Jean Margo Reid, Trustee Roscoe S. Suddarth, Trustee Richard R. West, Trustee Donald C. Burke, Vice President and Treasurer John M. Loffredo, Senior Vice President Karen Clark, Fund Chief Compliance Officer Alice A. Pellegrino, Secretary Custodian State Street Bank and Trust Company P.O. Box 351 Boston, MA 02101 Transfer Agent PFPC Inc. Wilmington, DE 19809 - -------------------------------------------------------------------------------- Effective January 1, 2007, Edward D. Zinbarg retired as a Trustee of BlackRock Intermediate Municipal Fund of BlackRock Municipal Series Trust. The Fund's Board of Trustees wishes Mr. Zinbarg well in his retirement. - -------------------------------------------------------------------------------- 2 BLACKROCK INTERMEDIATE MUNICIPAL FUND APRIL 30, 2007 A Letter to Shareholders Dear Shareholder In its first four months, 2007 could already be termed an eventful year for investors. For most financial markets, 2007 opened just as 2006 ended -- on a positive trajectory. Then, at the end of February and into March, global equity markets registered their first significant decline since last summer. The market jitters were triggered by a significant setback in the Chinese market and were exacerbated by worries of a weakening economy, escalating geopolitical concerns and rising delinquencies in the subprime mortgage market. Still, underlying stock market fundamentals appeared quite sound, supported by a generally favorable global economic backdrop, tame inflation, slowing but still positive earnings growth, relatively low interest rates and attractive valuations. These conditions prevailed later, and the Dow Jones Industrial Average crossed the 13,000 mark for the first time in its history in late April. Not unlike the equity market, the bond market also experienced volatility as observers attempted to interpret mixed economic signals. A bond market rally (falling yields and rising prices) late last year reversed itself early in 2007 amid some transitory signs of economic strength. Overall, yields have fluctuated month to month but ended April little changed from the beginning of the year. However, compared to one year ago, yields on 30-year Treasury bonds fell 36 basis points (.36%) and 10-year yields fell 44 basis points, while prices correspondingly rose. For its part, the Federal Reserve Board (the Fed) has left the target short-term interest rate on hold at 5.25% since first pausing in its interest rate-hiking campaign on August 8, 2006. The central bankers continue to express concern about potential inflationary pressures, but also acknowledge signs of economic weakness. Given this relatively "balanced" assessment, most observers believe the Fed will keep interest rates on hold for now. Against this backdrop, most major market indexes posted positive returns for the annual and semi-annual reporting periods ended April 30, 2007: Total Returns as of April 30, 2007 6-month 12-month =================================================================================================================== U.S. equities (Standard & Poor's 500 Index) + 8.60% +15.24% - ------------------------------------------------------------------------------------------------------------------- Small cap U.S. equities (Russell 2000 Index) + 6.86 + 7.83 - ------------------------------------------------------------------------------------------------------------------- International equities (MSCI Europe, Australasia, Far East Index) +15.46 +19.81 - ------------------------------------------------------------------------------------------------------------------- Fixed income (Lehman Brothers Aggregate Bond Index) + 2.64 + 7.36 - ------------------------------------------------------------------------------------------------------------------- Tax-exempt fixed income (Lehman Brothers Municipal Bond Index) + 1.59 + 5.78 - ------------------------------------------------------------------------------------------------------------------- High yield bonds (Lehman Brothers U.S. Corporate High Yield 2% Issuer Cap Index) + 6.96 +11.72 - ------------------------------------------------------------------------------------------------------------------- If the first four months are any guide, 2007 could be a year of enhanced market volatility. As you navigate the uncertainties, we encourage you to review your investment goals with your financial professional and to make portfolio changes, as needed. For more insight, we invite you to view "What's Ahead in 2007: An Investment Perspective" and "Are You Prepared for Volatility?" at www.blackrock.com/funds. We thank you for entrusting BlackRock with your investment assets, and we look forward to continuing to serve you in the months and years ahead. Sincerely, /s/ Robert C. Doll, Jr. Robert C. Doll, Jr. Fund President and Trustee BLACKROCK INTERMEDIATE MUNICIPAL FUND APRIL 30, 2007 3 A Discussion With Your Fund's Portfolio Managers We made strides in restructuring the portfolio in an effort to balance total return and current income for our shareholders. Describe the recent market environment relative to municipal bonds. Long-term bond yields traded in a fairly broad and volatile range over the past six months, only to end the period little changed. Overall, financial conditions have remained relatively balanced, with moderate economic activity and well-contained inflationary pressures. Recent commentary from the Federal Reserve Board (the Fed) has supported this trading range. The Fed is expected to maintain its "balanced" economic assessment at least into mid-year. During the six-month period ended April 30, 2007, 30-year U.S. Treasury bond yields rose nine basis points (.09%) to 4.81%, while 10-year Treasury note yields rose two basis points to 4.63%. Similarly, movements were fairly muted in the tax-exempt market. As measured by Municipal Market Data, yields on AAA-rated municipal bonds maturing in 30 years declined three basis points to 4.10%, and yields on AAA-rated municipal bonds maturing in 10 years rose 12 basis points to 3.76%. Investor demand for municipal product continued to strengthen throughout the six-month period. The Investment Company Institute reports that long-term municipal bond funds received over $8.7 billion in net new cash flows during the first three months of 2007, a 42% increase compared to the first three months of 2006. Weekly fund flows, as reported by AMG Data, also have risen. Weekly inflows during the April 2007 quarter averaged over $489 million, up from a weekly average of $400 million in fourth quarter 2006. The improving demand among retail investors reflects, in large part, increased acceptance of lower nominal yields and bond coupon structure. Throughout much of last year, retail-oriented municipal bond broker/dealers noted significant individual investor resistance to purchasing tax-exempt issues with yields below 4.50% and/or issues bearing nominal coupons below 5%. As tax-exempt bond yields have stabilized in recent months, it appears retail investors have become increasingly comfortable purchasing tax-exempt bonds with those characteristics, which has served to support the market's performance. In terms of supply, issuance of long-term municipal bonds has increased over the past six months. More than $225 billion in new bonds was issued during the April reporting period, an increase of over 30% compared to the same six months one year ago. Over the past three months, municipalities issued more than $106 billion in new long-term tax-exempt bonds, an increase of more than 32% compared to the same period a year ago. So far this year, greater than $135 billion in long-term municipal bonds has been underwritten, putting 2007 annual issuance some 4% ahead of 2005's record pace. Issuers have continued to take advantage of historically low interest rates to refinance outstanding issues. In the first four months of 2007, we have seen 10 underwritings exceeding $1 billion in size. These "mega-deals" have continued to be relatively easily absorbed by market participants, especially non-traditional and foreign buyers who find the liquidity afforded by these deals to be particularly attractive. Looking ahead, we believe investor demand will be critical in maintaining the tax-exempt market's strong technical position. The increase in new bond supply seen this year is unlikely to abate significantly, leading to record or near-record annual issuance. Relatively stable yield ratios compared to taxable bonds, coupled with a comparatively steep municipal yield curve, should help to sustain traditional and non-traditional investor interest in tax-exempt bonds and support the market's performance into mid-2007. How did the Fund perform during the period in light of the existing market conditions? For the six-month period ended April 30, 2007, BlackRock Intermediate Municipal Fund's Institutional, Investor A, Investor A1, Investor B and Investor C Shares had total returns of +1.28%, +1.15%, +1.13%, +1.12% and +.68%, respectively. (Fund results shown do not reflect sales charges and would be lower if sales charges were included. Complete performance information can be found on pages 6 and 7 of this report to shareholders.) For the same period, the broader municipal market, as measured by the Lehman Brothers Municipal Bond Index, returned +1.59% and the Lipper Intermediate Municipal Debt Funds category had an average return of +1.11%. (Funds in this Lipper category invest primarily in municipal debt issues with dollar-weighted average maturities in the area of five to 10 years.) Given its investment mandate, the Fund's performance will necessarily differ from that of the Lehman index. The portfolio concentrates its investments in the intermediate part of the municipal yield curve, whereas the Lehman index focuses on 4 BLACKROCK INTERMEDIATE MUNICIPAL FUND APRIL 30, 2007 longer-dated securities, which continued to outperform short- and intermediate-maturity bonds during this period as the yield curve flattened. The Fund's performance versus its comparable Lipper group was more favorable. Our long duration bias within the intermediate spectrum (specifically, 10 years - 12 years) proved advantageous on a relative basis. The Fund's attractive coupon structure also served the portfolio well in a period of stable to slightly rising interest rates. The Fund's average coupon is nearly 5.25%, compared to a market average of roughly 3.85% at period-end (as measured by the Municipal Market Data 10-year scale). What changes were made to the portfolio during the period? We made strides in restructuring the portfolio to align its holdings closer to that of the broader intermediate tax-exempt market. This involved a greater emphasis on current yield and lower-duration securities. As part of our restructuring efforts, we committed cash reserves held in the portfolio to the intermediate sector of the municipal market as opportunities presented themselves. This move is in keeping with the recommendation of our internal Municipal Investment Strategy Group, which has identified 10-year to 15-year municipal securities as having the greatest relative value on the curve. Here, we are able to capture decent yields without having to lock into longer maturities. In making these changes, we are targeting a more competitive current yield for our shareholders with limited fluctuation in the Fund's underlying net asset value. Having said that, the low absolute level of interest rates in the present market, combined with tight credit spreads and a historically flat yield curve, requires us to exercise patience in our efforts. The Fund began operations in a higher-rate environment; as such, current yields do little to improve on existing positions. In addition, the sale of older-dated positions usually requires the realization of a capital gain, something we try to avoid. Capital gains must be distributed to shareholders at fiscal year-end, resulting in a taxable event. Our goal is to manage the Fund in the most tax efficient manner. How would you characterize the Fund's position at the close of the period? The Fund ended the period with 4% of assets in cash equivalent reserves, monies that we will look to deploy in the municipal marketplace as opportunities arise to improve the portfolio's income distribution capacity. We maintain our focus on bonds with higher average coupons and structures that help to mute price volatility. We also intend to emphasize a high degree of credit quality in making new purchases. Given the tightness of credit spreads, we find that there is little additional yield to be gained from investing in lower-rated bonds. We are looking to accomplish all of this in an effort to deliver an efficient balance between total return and current income for our shareholders. Walter C. O'Connor, CFA Portfolio Manager Theodore R. Jaeckel Jr., CFA Portfolio Manager May 11, 2007 BLACKROCK INTERMEDIATE MUNICIPAL FUND APRIL 30, 2007 5 Performance Data About Fund Performance Effective October 2, 2006, the Fund's Class A, Class B and Class I Shares were redesignated Investor A1, Investor B and Institutional Shares, respectively. All Class C Shares converted to Class A (now Investor A1) Shares on August 25, 2006. As previously communicated to shareholders, new sales charge schedules came into effect at the same time for certain of these classes. The Fund has multiple classes of shares: o Institutional Shares are not subject to any sales charge. Institutional Shares bear no ongoing distribution or service fees and are available only to eligible investors. o Investor A Shares incur a maximum initial sales charge (front-end load) of 4.25% and a service fee of 0.25% per year (but no distribution fee). Investor A Shares commenced operations on October 2, 2006. Prior to Investor A Shares' inception, the returns for Investor A Shares were based upon the performance of the Fund's Institutional Shares. The returns for Investor A Shares, however, are adjusted to reflect the service (12b-1) fees applicable to Investor A Shares. o Investor A1 Shares incur a maximum initial sales charge (front-end load) of 1% and a service fee of 0.10% per year (but no distribution fee). o Investor B Shares are subject to a maximum contingent deferred sales charge of 1%, declining to 0% after three years. In addition, Investor B Shares are subject to a distribution fee of 0.10% per year and a service fee of 0.20% per year. These shares automatically convert to Investor A1 Shares after approximately 10 years. (There is no initial sales charge for automatic share conversions.) o Investor C Shares are subject to a distribution fee of 0.75% per year and a service fee of 0.25% per year. In addition, Investor C Shares are subject to a 1% contingent deferred sales charge if redeemed within one year of purchase. Investor C Shares commenced operations on October 2, 2006. Prior to Investor C Shares' inception, the returns for Investor C Shares were based upon the performance of the Fund's Institutional Shares. The returns for Investor C Shares, however, are adjusted to reflect the distribution and service (12b-1) fees applicable to Investor C Shares. Performance information reflects past performance and does not guarantee future results. Current performance may be lower or higher than the performance data quoted. Refer to www.blackrock.com to obtain performance data current to the most recent month-end. Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or the redemption of fund shares. Figures shown in each of the following tables assume reinvestment of all dividends and capital gain distributions, if any, at net asset value on the payable date. The Fund's investment adviser reimbursed a portion of the Fund's expenses. Without such reimbursement, the Fund's performance would have been lower. Investment return and principal value of shares will fluctuate so that shares, when redeemed, may be worth more or less than their original cost. Dividends paid to each class of shares will vary because of the different levels of service, distribution and transfer agency fees applicable to each class, which are deducted from the income available to be paid to shareholders. Recent Performance Results 6-Month 12-Month 10-Year Standardized As of April 30, 2007 Total Return Total Return Total Return 30-Day Yield ========================================================================================================================== Institutional Shares* +1.28% +4.98% +63.22% 3.47% - -------------------------------------------------------------------------------------------------------------------------- Investor A Shares* +1.15 +4.71 +59.21 3.10 - -------------------------------------------------------------------------------------------------------------------------- Investor A1 Shares* +1.13 +4.87 +61.47 3.34 - -------------------------------------------------------------------------------------------------------------------------- Investor B Shares* +1.12 +4.65 +58.22 3.15 - -------------------------------------------------------------------------------------------------------------------------- Investor C Shares* +0.68 +3.93 +47.73 2.47 - -------------------------------------------------------------------------------------------------------------------------- Lehman Brothers Municipal Bond Index** +1.59 +5.78 +75.88 -- - -------------------------------------------------------------------------------------------------------------------------- * Investment results shown do not reflect sales charges; results shown would be lower if a sales charge was included. Cumulative total investment returns are based on changes in net asset values for the periods shown, and assume reinvestment of all dividends and capital gains distributions at net asset value on the payable date. ** This unmanaged Index consists of revenue bonds, prerefunded bonds, general obligation bonds and insured bonds. 6 BLACKROCK INTERMEDIATE MUNICIPAL FUND APRIL 30, 2007 Performance Data (concluded) Intermediate Municipal Fund BlackRock Intermediate Municipal Fund -- Edgar Total Return Based on a $10,000 Investment A line graph depicting the growth of an investment in the Fund's Institutional, Investor A, Investor A1, Investor B & Investor C Shares compared to growth of an investment in the Lehman Brothers Municipal Bond Index. Values are from April 1997 to April 2007: Lehman Brothers Institutional Investor A Investor A1 Investor B Investor C Municipal Bond Shares*+ Shares*+ Shares*+ Shares*+ Shares*+ Index++ 4/97 $10,000 $9,575 $9,900 $10,000 $10,000 $10,000 4/98 $10,838 $10,352 $10,719 $10,804 $10,731 $10,930 4/99 $11,566 $11,019 $11,416 $11,482 $11,338 $11,689 4/00 $11,456 $10,888 $11,308 $11,349 $11,119 $11,582 4/01 $12,435 $11,789 $12,262 $12,280 $11,949 $12,783 4/02 $13,319 $12,596 $13,121 $13,112 $12,672 $13,678 4/03 $14,412 $13,595 $14,185 $14,145 $13,576 $14,840 4/04 $14,670 $13,804 $14,410 $14,353 $13,681 $15,237 4/05 $15,398 $14,453 $15,125 $15,019 $14,218 $16,276 4/06 $15,549 $14,558 $15,242 $15,119 $14,214 $16,627 4/07 $16,322 $15,244 $15,985 $15,822 $14,773 $17,588 * Assuming maximum sales charge, if any, transaction costs and other operating expenses, including advisory fees. + The Fund invests primarily in a diversified portfolio of investment grade obligations whose interest is exempt from federal income taxes, with a dollar-weighted average maturity from five to 12 years. ++ This unmanaged Index consists of revenue bonds, prerefunded bonds, general obligation bonds and insured bonds. Past performance is not indicative of future results. Average Annual Total Return Return ================================================================================ Institutional Shares ================================================================================ One Year Ended 4/30/07 +4.98% - -------------------------------------------------------------------------------- Five Years Ended 4/30/07 +4.15 - -------------------------------------------------------------------------------- Ten Years Ended 4/30/07 +5.02 - -------------------------------------------------------------------------------- Return Without Return With Sales Charge Sales Charge* ================================================================================ Investor A Shares ================================================================================ One Year Ended 4/30/07 +4.71% +0.26% - -------------------------------------------------------------------------------- Five Years Ended 4/30/07 +3.89 +2.99 - -------------------------------------------------------------------------------- Ten Years Ended 4/30/07 +4.76 +4.31 - -------------------------------------------------------------------------------- Return Without Return With Sales Charge Sales Charge** ================================================================================ Investor A1 Shares ================================================================================ One Year Ended 4/30/07 +4.87% +3.82% - -------------------------------------------------------------------------------- Five Years Ended 4/30/07 +4.03 +3.82 - -------------------------------------------------------------------------------- Ten Years Ended 4/30/07 +4.91 +4.80 - -------------------------------------------------------------------------------- Return Return Without CDSC With CDSC++ ================================================================================ Investor B Shares+ ================================================================================ One Year Ended 4/30/07 +4.65% +3.65% - -------------------------------------------------------------------------------- Five Years Ended 4/30/07 +3.83 +3.83 - -------------------------------------------------------------------------------- Ten Years Ended 4/30/07 +4.69 +4.69 - -------------------------------------------------------------------------------- Return Return Without CDSC With CDSC++ ================================================================================ Investor C Shares+++ ================================================================================ One Year Ended 4/30/07 +3.93% +2.93% - -------------------------------------------------------------------------------- Five Years Ended 4/30/07 +3.12 +3.12 - -------------------------------------------------------------------------------- Ten Years Ended 4/30/07 +3.98 +3.98 - -------------------------------------------------------------------------------- * Assuming maximum sales charge of 4.25%. ** Assuming maximum sales charge of 1%. + Maximum contingent deferred sales charge is 1% and is reduced to 0% after three years. ++ Assuming payment of applicable contingent deferred sales charge. +++ Maximum contingent deferred sales charge is 1% and is reduced to 0% after one year. BLACKROCK INTERMEDIATE MUNICIPAL FUND APRIL 30, 2007 7 Disclosure of Expenses Shareholders of this Fund may incur the following charges: (a) expenses related to transactions, including sales charges, redemption fees and exchange fees; and (b) operating expenses including advisory fees, distribution fees including 12b-1 fees, and other Fund expenses. The following example (which is based on a hypothetical investment of $1,000 invested on November 1, 2006 and held through April 30, 2007) is intended to assist shareholders both in calculating expenses based on an investment in the Fund and in comparing these expenses with similar costs of investing in other mutual funds. The first table below provides information about actual account values and actual expenses. In order to estimate the expenses a shareholder paid during the period covered by this report, shareholders can divide their account value by $1,000 and then multiply the result by the number in the first line under the heading entitled "Expenses Paid During the Period." The second table below provides information about hypothetical account values and hypothetical expenses based on the Fund's actual expense ratio and an assumed rate of return of 5% per year before expenses. In order to assist shareholders in comparing the ongoing expenses of investing in this Fund and other funds, compare the 5% hypothetical example with the 5% hypothetical examples that appear in other funds' shareholder reports. The expenses shown in the table are intended to highlight shareholders' ongoing costs only and do not reflect any transactional expenses, such as sales charges, redemption fees or exchange fees. Therefore, the second table is useful in comparing ongoing expenses only, and will not help shareholders determine the relative total expenses of owning different funds. If these transactional expenses were included, shareholder expenses would have been higher. Including Interest Expense and Fees Expenses Paid During the Period* Beginning Ending November 1, Account Value Account Value 2006 to November 1, 2006 April 30, 2007 April 30, 2007 ============================================================================================================================ Actual ============================================================================================================================ Institutional $1,000 $1,012.80 $4.89 - ---------------------------------------------------------------------------------------------------------------------------- Investor A $1,000 $1,011.50 $6.13 - ---------------------------------------------------------------------------------------------------------------------------- Investor A1 $1,000 $1,011.30 $5.39 - ---------------------------------------------------------------------------------------------------------------------------- Investor B $1,000 $1,011.20 $6.38 - ---------------------------------------------------------------------------------------------------------------------------- Investor C $1,000 $1,006.80 $9.90 ============================================================================================================================ Hypothetical (5% annual return before expenses)** ============================================================================================================================ Institutional $1,000 $1,019.94 $4.91 - ---------------------------------------------------------------------------------------------------------------------------- Investor A $1,000 $1,018.70 $6.16 - ---------------------------------------------------------------------------------------------------------------------------- Investor A1 $1,000 $1,019.44 $5.41 - ---------------------------------------------------------------------------------------------------------------------------- Investor B $1,000 $1,018.45 $6.41 - ---------------------------------------------------------------------------------------------------------------------------- Investor C $1,000 $1,014.93 $9.94 - ---------------------------------------------------------------------------------------------------------------------------- * For each class of the Fund, expenses are equal to the annualized expense ratio for the class (.98% for Institutional, 1.23% for Investor A, 1.08% for Investor A1, 1.28% for Investor B and 1.99% for Investor C), multiplied by the average account value over the period, multiplied by 181/365 (to reflect the one-half year period shown). ** Hypothetical 5% return before expenses is calculated by pro-rating the number of days in the most recent fiscal half year divided by 365. 8 BLACKROCK INTERMEDIATE MUNICIPAL FUND APRIL 30, 2007 Disclosure of Expenses (concluded) Excluding Interest Expense and Fees Expenses Paid During the Period* Beginning Ending November 1, Account Value Account Value 2006 to November 1, 2006 April 30, 2007 April 30, 2007 ========================================================================================================================= Actual ========================================================================================================================= Institutional $1,000 $1,012.80 $3.64 - ------------------------------------------------------------------------------------------------------------------------- Investor A $1,000 $1,011.50 $4.94 - ------------------------------------------------------------------------------------------------------------------------- Investor A1 $1,000 $1,011.30 $4.19 - ------------------------------------------------------------------------------------------------------------------------- Investor B $1,000 $1,011.20 $5.19 - ------------------------------------------------------------------------------------------------------------------------- Investor C $1,000 $1,006.80 $8.71 ========================================================================================================================= Hypothetical (5% annual return before expenses)** ========================================================================================================================= Institutional $1,000 $1,021.18 $3.66 - ------------------------------------------------------------------------------------------------------------------------- Investor A $1,000 $1,019.89 $3.66 - ------------------------------------------------------------------------------------------------------------------------- Investor A1 $1,000 $1,020.63 $4.21 - ------------------------------------------------------------------------------------------------------------------------- Investor B $1,000 $1,019.64 $5.21 - ------------------------------------------------------------------------------------------------------------------------- Investor C $1,000 $1,016.12 $8.75 - ------------------------------------------------------------------------------------------------------------------------- * For each class of the Fund, expenses are equal to the annualized expense ratio for the class (.73% for Institutional, .99% for Investor A, .84% for Investor A1, 1.04% for Investor B and 1.75% for Investor C), multiplied by the average account value over the period, multiplied by 181/365 (to reflect the one-half year period shown). ** Hypothetical 5% return before expenses is calculated by pro-rating the number of days in the most recent fiscal half year divided by 365. BLACKROCK INTERMEDIATE MUNICIPAL FUND APRIL 30, 2007 9 Schedule of Investments as of April 30, 2007 (Unaudited) (in Thousands) Face Amount Municipal Bonds Value ================================================================================ Alabama -- 0.3% $ 500 Tuscaloosa, Alabama, Special Care Facilities Financing Authority, Residential Care Facility Revenue Bonds (Capstone Village, Inc. Project), Series A, 5.125% due 8/01/2015 $ 494 ================================================================================ Alaska -- 1.2% 2,250 Alaska Student Loan Corporation, Student Loan Revenue Bonds, AMT, Series A, 5.65% due 7/01/2012 (a) 2,256 ================================================================================ Arizona -- 2.9% 5,000 Arizona State Transportation Board, Highway Revenue Bonds, Series B, 5% due 7/01/2017 5,416 ================================================================================ California -- 22.9% 875 Agua Caliente Band of Cahuilla Indians, California, Casino Revenue Bonds, 5.60% due 7/01/2013 911 2,000 Antelope Valley, California, Health Care District Revenue Bonds, VRDN, Series A, 5.25% due 9/01/2017 (g) 2,072 5,035 Bay Area Toll Authority, California, Toll Bridge Revenue Refunding Bonds (San Francisco Bay Area), Series F, 5% due 4/01/2017 5,470 5,225 California County Tobacco Securitization Agency, California, Tobacco Revenue Bonds (Los Angeles County Securitization Corporation), 5.25% due 6/01/2021 (i) 4,584 10,000 California State Department of Water Resources, Power Supply Revenue Bonds, Series A, 5.50% due 5/01/2014 (a) 10,911 California State, GO, Refunding: 5,000 5% due 3/01/2018 5,357 1,000 (Veterans Bonds), Series BG, 5.05% due 12/01/2011 1,030 5,000 Coast Community College District, California, GO (Election of 2002), Series B, 5% due 8/01/2018 (c) 5,429 3,000 Golden State Tobacco Securitization Corporation of California, Tobacco Settlement Revenue Refunding Bonds, Senior Series A-1, 5% due 6/01/2016 3,111 3,000 Los Angeles, California, Harbor Department Revenue Refunding Bonds, AMT, Series C, 5% due 8/01/2017 (e) 3,237 ================================================================================ Colorado -- 3.0% 5,000 Denver, Colorado, City and County Airport Revenue Bonds, AMT, Series D, 7.75% due 11/15/2013 (a) 5,602 ================================================================================ Florida -- 5.5% 2,720 Broward County, Florida, Airport System Revenue Bonds, AMT, Series L, 5% due 10/01/2018 (a) 2,883 4,000 Florida Hurricane Catastrophe Fund Financing Corporation Revenue Bonds, Series A, 5.25% due 7/01/2012 4,270 1,200 Martin County, Florida, PCR, Refunding (Florida Power & Light Company Project), VRDN, 4.05% due 7/15/2022 (g) 1,200 310 Middle Village Community Development District, Florida, Special Assessment Bonds, Series C, 5.125% due 5/01/2009 310 1,090 Panther Trace Community Development District II, Florida, Special Assessment Revenue Bonds, Series A, 5% due 11/01/2010 1,087 45 Reunion East Community Development District, Florida, Special Assessment, Series B, 5.90% due 11/01/2007 45 310 Sterling Hill, Florida, Community Development District, Capital Improvement Revenue Refunding Bonds, Series B, 5.50% due 11/01/2010 310 ================================================================================ Georgia -- 0.6% 1,050 Fulton County, Georgia, Residential Care Facilities, Revenue Refunding Bonds (Canterbury Court Project), Series A, 5% due 2/15/2014 1,053 ================================================================================ Idaho -- 2.9% 5,000 Ada and Canyon Counties, Idaho, Joint School District Number 2 (Meridian), GO, 5% due 8/15/2017 5,406 ================================================================================ Illinois -- 0.9% 1,000 Chicago, Illinois, Tax Allocation Bonds (Kingsbury Redevelopment Project), Series A, 6.57% due 2/15/2013 1,031 715 Illinois State Finance Authority Revenue Bonds (Primary Health Care Centers Program), 5.90% due 7/01/2014 731 ================================================================================ Massachusetts -- 5.6% 3,300 Massachusetts State Industrial Finance Agency, Resource Recovery Revenue Refunding Bonds (Ogden Haverhill Project), AMT, Series A, 5.30% due 12/01/2009 3,379 Massachusetts State Port Authority, Special Facilities Revenue Bonds (Delta Air Lines Inc. Project), AMT, Series A (a): 2,500 5.50% due 1/01/2014 2,646 4,000 5.50% due 1/01/2015 4,229 ================================================================================ Michigan -- 0.8% 1,555 Michigan State Strategic Fund, PCR (General Motors Corporation Project), VRDN, 7% due 12/01/2008 (g) 1,555 ================================================================================ Minnesota -- 3.0% 5,000 Minnesota State, GO, 5% due 6/01/2018 5,429 ================================================================================ Missouri -- 5.3% 4,000 Jackson County, Missouri, Special Obligation Revenue Bonds (Harry S. Truman Sports Complex Project), 5% due 12/01/2019 (a) 4,316 5,000 Missouri State Highways and Transportation Commission, First Lien State Road Revenue Bonds, Series A, 5% due 5/01/2017 5,423 ================================================================================ Portfolio Abbreviations To simplify the listings of BlackRock Intermediate Municipal Fund of BlackRock Municipal Series Trust's portfolio holdings in the Schedule of Investments, we have abbreviated the names of many of the securities according to the list at right. AMT Alternative Minimum Tax (subject to) GAN Grant Anticipation Notes GO General Obligation Bonds HDA Housing Development Authority IDA Industrial Development Authority PCR Pollution Control Revenue Bonds VRDN Variable Rate Demand Notes 10 BLACKROCK INTERMEDIATE MUNICIPAL FUND APRIL 30, 2007 Schedule of Investments (continued) (in Thousands) Face Amount Municipal Bonds Value =============================================================================== Montana -- 2.1% $ 3,500 Montana State Department of Transportation Revenue Bonds (Highway 93 Advance Construction Project), GAN, 5.25% due 6/01/2016 (e) $ 3,848 =============================================================================== New York -- 1.2% 1,140 New York State Dormitory Authority, Non-State Supported Debt, Revenue Refunding Bonds (New York University Hospital Center), Series A, 5% due 7/01/2016 1,192 1,000 Westchester County, New York, IDA, Continuing Care Retirement, Mortgage Revenue Bonds (Kendal on the Hudson Project), Series A, 5.625% due 1/01/2013 1,038 =============================================================================== North Carolina -- 3.0% 5,000 North Carolina State, GO, Refunding, Series B, 5% due 4/01/2017 5,495 =============================================================================== Oregon -- 2.9% 5,000 Oregon State Department of Transportation, Highway User Tax Revenue Bonds, Series A, 5% due 11/15/2017 5,440 =============================================================================== Pennsylvania -- 2.9% 5,000 Pennsylvania State Higher Educational Facilities Authority, Revenue Refunding Bonds (University Pennsylvania Health System), Series A, 5% due 8/15/2016 (a) 5,374 =============================================================================== South Carolina -- 2.8% 5,000 South Carolina State, Highway GO, Series A, 4.60% due 5/01/2014 5,171 =============================================================================== Tennessee -- 2.2% 300 Sevier County, Tennessee, Public Building Authority, Local Government Improvement Revenue Refunding Bonds, VRDN, Series IV-H-1, 4.12% due 6/01/2025 (a)(g) 300 Sevier County, Tennessee, Public Building Authority, Local Government Public Improvement Revenue Bonds, VRDN (g): 1,255 Series IV-A-2, 4.03% due 6/01/2025 (c) 1,255 850 Series IV-E-1, 4.03% due 6/01/2030 (a) 850 1,600 Tennessee HDA, Revenue Bonds (Homeownership Program), AMT, Series 2-C, 5.85% due 7/01/2009 1,612 =============================================================================== Texas -- 6.2% 2,000 Brazos River Authority, Texas, Revenue Refunding Bonds (Reliant Energy, Inc. Project), Series B, 7.75% due 12/01/2018 2,098 5,000 Dallas-Fort Worth, Texas, International Airport Revenue Refunding and Improvement Bonds, AMT, Series A, 5.75% due 11/01/2014 (b) 5,356 3,640 University of Texas, Financing System Revenue Refunding Bonds, Series B, 5% due 8/15/2018 3,924 =============================================================================== Virginia -- 2.9% 5,000 Virginia State Public School Authority Revenue Bonds, Series A, 5% due 8/01/2017 5,435 =============================================================================== Washington -- 6.1% 5,400 Energy Northwest, Washington, Electric Revenue Refunding Bonds (Columbia Generating), Series A, 5.50% due 7/01/2017 (c) 5,800 5,000 Pierce County, Washington, School District Number 3 (Puyallup), GO, 5% due 12/01/2017 (e) 5,388 =============================================================================== Puerto Rico -- 0.9% 1,500 Puerto Rico Commonwealth Government Development Bank, Senior Revenue Bonds, Series B, 5% due 12/01/2017 1,603 - ------------------------------------------------------------------------------- Total Municipal Bonds (Cost -- $159,272) -- 88.1% 162,362 =============================================================================== =============================================================================== Municipal Bonds Held in Trust (h) =============================================================================== Illinois -- 5.8% 5,000 Chicago, Illinois, O'Hare International Airport, General Airport Revenue Refunding Bonds, Third Lien, AMT, Series A-2, 5.25% due 1/01/2013 (c) 5,325 5,000 Chicago, Illinois, O'Hare International Airport Revenue Refunding Bonds, 3rd Lien, AMT, Series A-2, 5.25% due 1/01/2014 (c) 5,325 =============================================================================== New Jersey -- 5.5% Port Authority of New York and New Jersey, Revenue Refunding Bonds, AMT, 120th Series (e): 5,000 5.75% due 10/15/2013 5,091 5,000 5.75% due 10/15/2014 5,091 - ------------------------------------------------------------------------------- Total Municipal Bonds Held in Trust (Cost -- $20,671) -- 11.3% 20,832 =============================================================================== =============================================================================== Shares Held Mutual Funds =============================================================================== 244 BlackRock Insured Municipal 2008 Term Trust, Inc. (d) 3,692 100 BlackRock Insured Municipal Term Trust, Inc. (d) 983 - ------------------------------------------------------------------------------- Total Mutual Funds (Cost -- $5,249) -- 2.6% 4,675 =============================================================================== =============================================================================== Short-Term Securities =============================================================================== 19 Merrill Lynch Institutional Tax-Exempt Fund, 3.70% (d)(f) 19 - ------------------------------------------------------------------------------- Total Short-Term Securities (Cost -- $19) -- 0.0% 19 =============================================================================== Total Investments (Cost -- $185,211*) -- 102.0% 187,888 Other Assets Less Liabilities -- 3.5% 6,374 Liability for Trust Certificates, Including Interest Expense Payable -- (5.5%) (10,070) -------- Net Assets -- 100.0% $184,192 ======== BLACKROCK INTERMEDIATE MUNICIPAL FUND APRIL 30, 2007 11 Schedule of Investments (concluded) (in Thousands) * The cost and unrealized appreciation (depreciation) of investments as of April 30, 2007, as computed for federal income tax purposes, were as follows: Aggregate cost ............................................ $ 175,754 ========= Gross unrealized appreciation ............................. $ 3,359 Gross unrealized depreciation ............................. (1,225) --------- Net unrealized appreciation ............................... $ 2,134 ========= (a) AMBAC Insured. (b) FGIC Insured. (c) FSA Insured. (d) Investments in companies considered to be an affiliate of the Fund, for purposes of Section 2(a)(3) of the Investment Company Act of 1940, were as follows: -------------------------------------------------------------------------- Net Dividend Affiliate Activity Income -------------------------------------------------------------------------- Merrill Lynch Institutional Tax-Exempt Fund -- $ -- + BlackRock Insured Municipal 2008 Term Trust, Inc. -- $ 95 BlackRock Insured Municipal Term Trust, Inc. -- $ 18 BlackRock Municipal Target Term Trust (344) $156 -------------------------------------------------------------------------- + Income was less than $1,000. (e) MBIA Insured. (f) Represents the current yield as of April 30, 2007. (g) Security may have a maturity of more than one year at time of issuance, but has variable rate and demand features that qualify it as a short-term security. The rate disclosed is that currently in effect. This rate changes periodically based upon prevailing market rates. (h) Securities represent underlying bonds transferred to a separate securitization trust established in a tender option bond transaction in which the Fund may have acquired the residual interest certificates. These securities serve as collateral in a financing transaction. See note 1(c) to Financial Statements for details of Municipal Bonds Held in Trust. (i) Represents a zero coupon bond; the interest rate shown reflects the effective yield. o Forward interest rate swaps outstanding as of April 30, 2007 were as follows: -------------------------------------------------------------------------- Notional Unrealized Amount Depreciation -------------------------------------------------------------------------- Pay a fixed rate of 3.70% and receive a floating rate based on a 1-week Bond Market Association rate Broker, Citibank N.A. Expires July 2017 $15,000 $(50) -------------------------------------------------------------------------- See Notes to Financial Statements. 12 BLACKROCK INTERMEDIATE MUNICIPAL FUND APRIL 30, 2007 Statement of Assets and Liabilities As of April 30, 2007 (Unaudited) ================================================================================================================================== Assets - ---------------------------------------------------------------------------------------------------------------------------------- Investments in unaffiliated securities, at value (identified cost -- $179,941,772) .. $ 183,194,042 Investments in affiliated securities, at value (identified cost -- $5,268,993) ...... 4,694,130 Cash ................................................................................ 7,747 Receivables: Securities sold ................................................................. $ 5,981,539 Interest ........................................................................ 2,802,247 Beneficial interests sold ....................................................... 776,496 Dividends ....................................................................... 17,917 9,578,199 ------------- Prepaid expenses and other assets ................................................... 32,851 ------------- Total assets ........................................................................ 197,506,969 ------------- ================================================================================================================================== Liabilities - ---------------------------------------------------------------------------------------------------------------------------------- Trust certificates .................................................................. 10,000,000 Unrealized depreciation on forward interest rate swaps .............................. 49,875 Payables: Securities purchased ............................................................ 2,087,345 Dividends to shareholders ....................................................... 532,633 Beneficial interest redeemed .................................................... 429,622 Investment adviser .............................................................. 75,249 Interest expense payable ........................................................ 69,625 Distributor ..................................................................... 8,662 Other affiliates ................................................................ 3,214 3,206,350 ------------- Accrued expenses .................................................................... 59,190 ------------- Total liabilities ................................................................... 13,315,415 ------------- ================================================================================================================================== Net Assets - ---------------------------------------------------------------------------------------------------------------------------------- Net assets .......................................................................... $ 184,191,554 ============= ================================================================================================================================== Net Assets Consist of - ---------------------------------------------------------------------------------------------------------------------------------- Institutional Shares of beneficial interest, $.10 par value, unlimited number of shares authorized ................................................................. $ 1,063,799 Investor A Shares of beneficial interest, $.10 par value, unlimited number of shares authorized ................................................................. 18,302 Investor A1 Shares of beneficial interest, $.10 par value, unlimited number of shares authorized ................................................................. 624,879 Investor B Shares of beneficial interest, $.10 par value, unlimited number of shares authorized ................................................................. 79,974 Investor C Shares of beneficial interest, $.10 par value, unlimited number of shares authorized ................................................................. 15,857 Paid-in capital in excess of par .................................................... 182,037,296 Accumulated distributions in excess of investment income -- net ..................... $ (107,350) Accumulated realized capital losses -- net .......................................... (2,168,735) Unrealized appreciation -- net ...................................................... 2,627,532 ------------- Total accumulated earnings -- net ................................................... 351,447 ------------- Net Assets .......................................................................... $ 184,191,554 ============= ================================================================================================================================== Net Asset Value - ---------------------------------------------------------------------------------------------------------------------------------- Institutional -- Based on net assets of $108,706,965 and 10,637,991 shares of beneficial interest outstanding ................................................... $ 10.22 ============= Investor A -- Based on net assets of $1,868,808 and 183,024 shares of beneficial interest outstanding .............................................................. $ 10.21 ============= Investor A1 -- Based on net assets of $63,824,801 and 6,248,791 shares of beneficial interest outstanding .............................................................. $ 10.21 ============= Investor B -- Based on net assets of $8,171,241 and 799,744 shares of beneficial interest outstanding .............................................................. $ 10.22 ============= Investor C -- Based on net assets of $1,619,739 and 158,574 shares of beneficial interest outstanding .............................................................. $ 10.21 ============= See Notes to Financial Statements. BLACKROCK INTERMEDIATE MUNICIPAL FUND APRIL 30, 2007 13 Statement of Operations For the Six Months Ended April 30, 2007 (Unaudited) ================================================================================================================================== Investment Income - ---------------------------------------------------------------------------------------------------------------------------------- Interest ............................................................................ $ 3,847,197 Dividends from affiliates ........................................................... 268,571 ------------- Total income ........................................................................ 4,115,768 ------------- ================================================================================================================================== Expenses - ---------------------------------------------------------------------------------------------------------------------------------- Investment advisory fees ............................................................ $ 496,092 Interest expense and fees ........................................................... 218,400 Accounting services ................................................................. 55,530 Printing and shareholder reports .................................................... 37,814 Service fees -- Investor A1 ......................................................... 33,348 Professional fees ................................................................... 30,261 Registration fees ................................................................... 22,430 Transfer agent fees -- Institutional ................................................ 14,297 Service and distribution fees -- Investor B ......................................... 13,227 Trustees' fees and expenses ......................................................... 12,253 Transfer agent fees -- Investor A1 .................................................. 8,814 Custodian fees ...................................................................... 7,154 Pricing fees ........................................................................ 4,507 Service and distribution fees -- Investor C ......................................... 3,820 Transfer agent fees -- Investor B ................................................... 1,589 Service fees -- Investor A .......................................................... 1,555 Transfer agent fees -- Investor A ................................................... 172 Transfer agent fees -- Investor C ................................................... 131 Other ............................................................................... 16,770 ------------- Total expenses before waiver and reimbursement ...................................... 978,164 Waiver and reimbursement of expenses ................................................ (45,119) ------------- Total expenses after waiver and reimbursement ....................................... 933,045 ------------- Investment income -- net ............................................................ 3,182,723 ------------- ================================================================================================================================== Realized & Unrealized Gain (Loss) -- Net - ---------------------------------------------------------------------------------------------------------------------------------- Realized loss on: Investments -- net .............................................................. (4,585) Forward interest rate swaps -- net .............................................. (198,200) (202,785) ------------- Change in unrealized appreciation/depreciation on: Investments -- net .............................................................. (1,001,119) Forward interest rate swaps -- net .............................................. 202,107 (799,012) ------------------------------ Total realized and unrealized loss -- net ........................................... (1,001,797) ------------- Net Increase in Net Assets Resulting from Operations ................................ $ 2,180,926 ============= See Notes to Financial Statements. 14 BLACKROCK INTERMEDIATE MUNICIPAL FUND APRIL 30, 2007 Statements of Changes in Net Assets For the Six Months Ended For the April 30, Year Ended 2007 October 31, Increase (Decrease) in Net Assets: (Unaudited) 2006 ================================================================================================================================== Operations - ---------------------------------------------------------------------------------------------------------------------------------- Investment income -- net ............................................................ $ 3,182,723 $ 6,463,395 Realized loss -- net ................................................................ (202,785) (1,688,727) Change in unrealized appreciation/depreciation -- net ............................... (799,012) 4,081,586 ------------------------------ Net increase in net assets resulting from operations ................................ 2,180,926 8,856,254 ------------------------------ ================================================================================================================================== Dividends & Distributions to Shareholders - ---------------------------------------------------------------------------------------------------------------------------------- Investment income -- net: Institutional ................................................................... (1,925,203) (3,600,332) Investor A ...................................................................... (21,304) (243) Investor A1 ..................................................................... (1,218,422) (1,810,323) Investor B ...................................................................... (151,983) (405,591) Investor C ...................................................................... (10,095) (206) Class C ......................................................................... -- (646,700) Realized gain -- net: Institutional ................................................................... -- (2,007,396) Investor A1 ..................................................................... -- (969,703) Investor B ...................................................................... -- (284,047) Class C ......................................................................... -- (491,006) ------------------------------ Net decrease in net assets resulting from dividends and distributions to shareholders (3,327,007) (10,215,547) ------------------------------ ================================================================================================================================== Beneficial Interest Transactions - ---------------------------------------------------------------------------------------------------------------------------------- Net increase (decrease) in net assets derived from beneficial interest transactions . 4,205,170 (8,046,361) ------------------------------ ================================================================================================================================== Net Assets - ---------------------------------------------------------------------------------------------------------------------------------- Total increase (decrease) in net assets ............................................. 3,059,089 (9,405,654) Beginning of period ................................................................. 181,132,465 190,538,119 ------------------------------ End of period* ...................................................................... $ 184,191,554 $ 181,132,465 ------------------------------ * Undistributed (accumulated distributions in excess of) investment income -- net $ (107,350) $ 36,934 ============================== See Notes to Financial Statements. BLACKROCK INTERMEDIATE MUNICIPAL FUND APRIL 30, 2007 15 Financial Highlights Institutional Investor A ------------------------------------------------------------ -------------------------- For the Six For the Six Months Months For the Ended Ended Period The following per share data and April 30, For the Year Ended October 31, April 30, Oct. 2, 2006++ ratios have been derived from information 2007 ------------------------------------------------ 2007 to Oct. 31, provided in the financial statements. (Unaudited) 2006 2005 2004 2003 2002 (Unaudited) 2006 ==================================================================================================================================== Per Share Operating Performance - ------------------------------------------------------------------------------------------------------------------------------------ Net asset value, beginning of period ..... $ 10.28 $ 10.36 $ 10.76 $ 10.71 $ 10.69 $ 10.60 $ 10.27 $ 10.26 ------------------------------------------------------------ ------------------------ Investment income -- net ................. .18+ .37+ .38+ .40+ .40+ .40 .17+ .02+ Realized and unrealized gain (loss) -- net (.05) .13 (.34) .08 .10 .13 (.05) .02 ------------------------------------------------------------ ------------------------ Total from investment operations ......... .13 .50 .04 .48 .50 .53 .12 .04 ------------------------------------------------------------ ------------------------ Less dividends and distributions: Investment income -- net ............. (.19) (.37) (.38) (.40) (.41) (.40) (.18) (.03) Realized gain -- net ................. -- (.21) (.06) (.03) (.07) (.04) -- -- ------------------------------------------------------------ ------------------------ Total dividends and distributions ........ (.19) (.58) (.44) (.43) (.48) (.44) (.18) (.03) ------------------------------------------------------------ ------------------------ Net asset value, end of period ........... $ 10.22 $ 10.28 $ 10.36 $ 10.76 $ 10.71 $ 10.69 $ 10.21 $ 10.27 ============================================================ ======================== ==================================================================================================================================== Total Investment Return** - ------------------------------------------------------------------------------------------------------------------------------------ Based on net asset value per share ....... 1.28%@ 4.96% .40% 4.57% 4.77% 5.16% 1.15%@ .36%@ ============================================================ ======================== ==================================================================================================================================== Ratios to Average Net Assets Applicable to Common Stock - ------------------------------------------------------------------------------------------------------------------------------------ Expenses, net of waiver and reimbursement and excluding interest expense and fees .73%* .73% .74% .79% .85% .89% .99%* .97%* ============================================================ ======================== Expenses, net of waiver and reimbursement .98%* 1.11% 1.00% .91% .94% 1.02% 1.23%* 1.34%* ============================================================ ======================== Expenses ................................. 1.03%* 1.16% 1.05% .94% .96% 1.02% 1.28%* 1.39%* ============================================================ ======================== Investment income -- net ................. 3.59%* 3.61% 3.63% 3.76% 3.80% 3.84% 3.30%* 3.08%* ============================================================ ======================== ==================================================================================================================================== Supplemental Data - ------------------------------------------------------------------------------------------------------------------------------------ Net assets, end of period (in thousands) . $108,707 $99,678 $100,831 $78,777 $44,372 $34,066 $ 1,869 $ 160 ============================================================ ======================== Portfolio turnover ....................... 14% 102% 162% 176% 179% 181% 14% 102% ============================================================ ======================== * Annualized. ** Total investment returns exclude the effects of any sales charges. + Based on average shares outstanding. ++ Commencement of operations. @ Aggregate total investment return. See Notes to Financial Statements. 16 BLACKROCK INTERMEDIATE MUNICIPAL FUND APRIL 30, 2007 Financial Highlights (continued) Investor A1 --------------------------------------------------------------------------------- For the Six Months Ended The following per share data and April 30, For the Year Ended October 31, ratios have been derived from information 2007 ---------------------------------------------------------------- provided in the financial statements. (Unaudited) 2006 2005 2004 2003 2002 ============================================================================================================================= Per Share Operating Performance - ----------------------------------------------------------------------------------------------------------------------------- Net asset value, beginning of period . $ 10.28 $ 10.35 $ 10.76 $ 10.71 $ 10.69 $ 10.60 ------------------------------------------------------------------------------- Investment income -- net ............. .18+ .35+ .38+ .39+ .40+ .39 Realized and unrealized gain (loss) -- net ...................... (.06) .15 (.36) .08 .09 .13 ------------------------------------------------------------------------------- Total from investment operations ..... .12 .50 .02 .47 .49 .52 ------------------------------------------------------------------------------- Less dividends and distributions: Investment income -- net ......... (.19) (.36) (.37) (.39) (.40) (.39) Realized gain -- net ............. -- (.21) (.06) (.03) (.07) (.04) ------------------------------------------------------------------------------- Total dividends and distributions .... (.19) (.57) (.43) (.42) (.47) (.43) ------------------------------------------------------------------------------- Net asset value, end of period ....... $ 10.21 $ 10.28 $ 10.35 $ 10.76 $ 10.71 $ 10.69 =============================================================================== ============================================================================================================================= Total Investment Return** - ----------------------------------------------------------------------------------------------------------------------------- Based on net asset value per share ... 1.13%@ 4.96% .20% 4.47% 4.68% 5.05% =============================================================================== ============================================================================================================================= Ratios to Average Net Assets Applicable to Common Stock - ----------------------------------------------------------------------------------------------------------------------------- Expenses, net of waiver and reimbursement and excluding interest expense and fees ................... .84%* .83% .84% .89% .95% .99% =============================================================================== Expenses, net of waiver and reimbursement ...................... 1.08%* 1.20% 1.11% 1.01% 1.04% 1.12% =============================================================================== Expenses ............................. 1.13%* 1.25% 1.16% 1.04% 1.06% 1.12% =============================================================================== Investment income -- net ............. 3.49%* 3.50% 3.54% 3.66% 3.70% 3.73% =============================================================================== ============================================================================================================================= Supplemental Data - ----------------------------------------------------------------------------------------------------------------------------- Net assets, end of period (in thousands) ..................... $ 63,825 $ 71,327 $ 48,524 $ 55,128 $ 51,786 $ 45,563 =============================================================================== Portfolio turnover ................... 14% 102% 162% 176% 179% 181% =============================================================================== * Annualized. ** Total investment returns exclude the effects of sales charges. + Based on average shares outstanding. @ Aggregate total investment return. See Notes to Financial Statements. BLACKROCK INTERMEDIATE MUNICIPAL FUND APRIL 30, 2007 17 Financial Highlights (continued) Investor B --------------------------------------------------------------------------------- For the Six Months Ended The following per share data and April 30, For the Year Ended October 31, ratios have been derived from information 2007 ---------------------------------------------------------------- provided in the financial statements. (Unaudited) 2006 2005 2004 2003 2002 ============================================================================================================================= Per Share Operating Performance - ----------------------------------------------------------------------------------------------------------------------------- Net asset value, beginning of period . $ 10.28 $ 10.36 $ 10.76 $ 10.71 $ 10.69 $ 10.60 ------------------------------------------------------------------------------- Investment income -- net ............. .17+ .34+ .35+ .37+ .38+ .37 Realized and unrealized gain (loss) -- net ...................... (.06) .15 (.34) .08 .09 .13 ------------------------------------------------------------------------------- Total from investment operations ..... .11 .49 .01 .45 .47 .50 ------------------------------------------------------------------------------- Less dividends and distributions: Investment income -- net ......... (.17) (.36) (.35) (.37) (.38) (.37) Realized gain -- net ............. -- (.21) (.06) (.03) (.07) (.04) ------------------------------------------------------------------------------- Total dividends and distributions .... (.17) (.57) (.41) (.40) (.45) (.41) ------------------------------------------------------------------------------- Net asset value, end of period ....... $ 10.22 $ 10.28 $ 10.36 $ 10.76 $ 10.71 $ 10.69 =============================================================================== ============================================================================================================================= Total Investment Return** - ----------------------------------------------------------------------------------------------------------------------------- Based on net asset value per share ... 1.12%@ 4.64% .08% 4.24% 4.46% 4.83% =============================================================================== ============================================================================================================================= Ratios to Average Net Assets Applicable to Common Stock - ----------------------------------------------------------------------------------------------------------------------------- Expenses, net of waiver and reimbursement and excluding interest expense and fees ................... 1.04%* 1.05% 1.05% 1.10% 1.17% 1.21% =============================================================================== Expenses, net of waiver and reimbursement ...................... 1.28%* 1.42% 1.32% 1.22% 1.26% 1.33% =============================================================================== Expenses ............................. 1.33%* 1.47% 1.37% 1.25% 1.27% 1.34% =============================================================================== Investment income -- net ............. 3.28%* 3.30% 3.34% 3.45% 3.48% 3.53% =============================================================================== ============================================================================================================================= Supplemental Data - ----------------------------------------------------------------------------------------------------------------------------- Net assets, end of period (in thousands) ......................... $ 8,171 $ 9,760 $ 14,982 $ 21,623 $ 28,678 $ 37,155 =============================================================================== Portfolio turnover ................... 14% 102% 162% 176% 179% 181% =============================================================================== * Annualized. ** Total investment returns exclude the effects of sales charges. + Based on average shares outstanding. @ Aggregate total investment return. See Notes to Financial Statements. 18 BLACKROCK INTERMEDIATE MUNICIPAL FUND APRIL 30, 2007 Financial Highlights (concluded) Investor C ----------------------------- For the Six Months For the Ended Period April 30, Oct. 2, 2006+ The following per share data and ratios have been derived 2007 to Oct. 31, from information provided in the financial statements. (Unaudited) 2006 ================================================================================================================================== Per Share Operating Performance - ---------------------------------------------------------------------------------------------------------------------------------- Net asset value, beginning of period ............................................ $ 10.28 $ 10.26 ---------------------------- Investment income -- net*** ..................................................... .11 .01 Realized and unrealized gain (loss) -- net ...................................... (.04) .03 ---------------------------- Total from investment operations ................................................ .07 .04 ---------------------------- Less dividends from investment income -- net .................................... (.14) (.02) ---------------------------- Net asset value, end of period .................................................. $ 10.21 $ 10.28 ============================ ================================================================================================================================== Total Investment Return** - ---------------------------------------------------------------------------------------------------------------------------------- Based on net asset value per share .............................................. .68%@ .40%@ ============================ ================================================================================================================================== Ratios to Average Net Assets Applicable to Common Stock - ---------------------------------------------------------------------------------------------------------------------------------- Expenses, net of waiver and reimbursement and excluding interest expense and fees 1.75%* 1.73%* ============================ Expenses, net of waiver and reimbursement ....................................... 1.99%* 2.09%* ============================ Expenses ........................................................................ 2.04%* 2.14%* ============================ Investment income -- net ........................................................ 2.51%* 2.36%* ============================ ================================================================================================================================== Supplemental Data - ---------------------------------------------------------------------------------------------------------------------------------- Net assets, end of period (in thousands) ........................................ $ 1,620 $ 207 ============================ Portfolio turnover .............................................................. 14% 102% ============================ * Annualized. ** Total investment returns exclude the effects of sales charges. *** Based on average shares outstanding. + Commencement of operations. @ Aggregate total investment return. See Notes to Financial Statements. BLACKROCK INTERMEDIATE MUNICIPAL FUND APRIL 30, 2007 19 Notes to Financial Statements (Unaudited) 1. Significant Accounting Policies: BlackRock Intermediate Municipal Fund (the "Fund") is presently the only series of BlackRock Municipal Series Trust (the "Trust"). The Fund is registered under the Investment Company Act of 1940, as amended, as a diversified, open-end management investment company. The Fund's financial statements are prepared in conformity with U.S. generally accepted accounting principles, which may require the use of management accruals and estimates. Actual results may differ from these estimates. These unaudited financial statements reflect all adjustments, which are, in the opinion of management, necessary to present a fair statement of the results for the interim period. All such adjustments are of a normal, recurring nature. The Fund offers multiple classes of shares. Institutional Shares are sold only to certain eligible investors. Investor A Shares are sold with a front-end sales charge. Investor A1 Shares are not generally available except for dividend and capital gains investment. Shares of Investor B and Investor C may be subject to a contingent deferred sales charge. All classes of shares have identical voting, dividend, liquidation and other rights and the same terms and conditions, except that Investor A, Investor A1, Investor B and Investor C Shares bear certain expenses related to the shareholder servicing of such shares, and Investor B and Investor C Shares also bear certain expenses related to the distribution of such shares. Each class has exclusive voting rights with respect to matters relating to its shareholder servicing and distribution expenditures (except that Investor B shareholders may vote on material changes to the Investor A1 distribution plan). Income, expenses (other than expenses attributable to a specific class) and realized and unrealized gains and losses are allocated daily to each class based on its relative net assets. The following is a summary of significant accounting policies followed by the Fund. (a) Valuation of investments -- Municipal bonds are traded primarily in the over-the-counter ("OTC") markets and are valued at the last available bid price in the OTC market or on the basis of values as obtained by a pricing service. Pricing services use valuation matrixes that incorporate both dealer-supplied valuations and valuation models. The procedures of the pricing service and its valuations are reviewed by the officers of the Fund under the general direction of the Board of Trustees. Such valuations and procedures are reviewed periodically by the Board of Trustees of the Fund. Financial futures contracts and options thereon, which are traded on exchanges, are valued at their closing prices as of the close of such exchanges. Options written or purchased are valued at the last sale price in the case of exchange-traded options. Options traded in the OTC market are valued at the last asked price (options written) or the last bid price (options purchased). Swap agreements are valued by quoted fair values received daily by the Fund's pricing service. Investments in open-end investment companies are valued at their net asset value each business day. Securities and other assets for which market quotations are not readily available are valued at fair value as determined in good faith by or under the direction of the Board of Trustees of the Fund. (b) Derivative financial instruments -- The Fund may engage in various portfolio investment strategies both to increase the return of the Fund and to hedge, or protect, its exposure to interest rate movements and movements in the securities markets. Losses may arise due to changes in the value of the contract or if the counterparty does not perform under the contract. o Financial futures contracts -- The Fund may purchase or sell financial futures contracts and options on such financial futures contracts. Financial futures contracts are contracts for delayed delivery of securities at a specific future date and at a specific price or yield. Upon entering into a contract, the Fund deposits and maintains as collateral, such initial margin as required by the exchange on which the transaction is effected. Pursuant to the contract, the Fund agrees to receive from or pay to the broker an amount of cash equal to the daily fluctuation in value of the contract. Such receipts or payments are known as variation margin and are recorded by the Fund as unrealized gains or losses. When the contract is closed, the Fund records a realized gain or loss equal to the difference between the value of the contract at the time it was opened and the value at the time it was closed. o Forward interest rate swaps -- The Fund may enter into forward interest rate swaps. In a forward interest rate swap, the Fund and the counterparty agree to make periodic net payments on a specified notional contract amount, commencing on a specified future effective date, unless terminated earlier. When the agreement is closed, the Fund records a realized gain or loss in an amount equal to the value of the agreement. o Swaps -- The Fund may enter into swap agreements, which are OTC contracts in which the Fund and a counterparty agree to make periodic net payments on a specified notional amount. The net payments can be made for a set period of time or may be triggered by a predetermined credit event. The net periodic payments may be based on a fixed or variable interest rate; the change in market value of a specified security, basket of securities or index; or the return generated by a security. 20 BLACKROCK INTERMEDIATE MUNICIPAL FUND APRIL 30, 2007 Notes to Financial Statements (continued) These periodic payments received or made by the Fund are recorded in the accompanying Statement of Operations as realized gains or losses, respectively. Gains or losses are also realized upon termination of the swap agreements. Swaps are marked-to-market daily and changes in value are recorded as unrealized appreciation (depreciation). Risks include changes in the returns of the underlying instruments, failure of the counterparties to perform under the contracts' terms and the possible lack of liquidity with respect to the swap agreements. (c) Municipal bonds held in trust -- The Fund invests in leveraged residual certificates ("TOB Residuals") issued by tender option bond trusts ("TOBs"). A TOB is established by a third party sponsor forming a special purpose entity, into which the Fund, or an agent on behalf of the Fund, transfers municipal securities. A TOB typically issues two classes of beneficial interests: short-term floating rate certificates, which are sold to third party investors, and residual certificates, which are generally issued to the Fund which made the transfer or to affiliates of the Fund. The Fund's transfers of the municipal securities to a TOB do not qualify for sale treatment under Statement of Financial Accounting Standards No. 140 "Accounting for Transfers and Servicing of Financial Assets and Extinguishments of Liabilities," therefore the municipal securities deposited into a TOB are presented in the Fund's schedule of investments and the proceeds from the transaction are reported as a liability for trust certificates of the Fund. Similarly, proceeds from residual certificates issued to affiliates, if any, from the transaction are included in the liability for trust certificates. Interest income from the underlying security is recorded by the Fund on an accrual basis. Interest expense incurred on the secured borrowing and other expenses related to remarketing, administration and trustee services to a TOB are reported as expenses of the Fund. The floating rate certificates have interest rates that generally reset weekly and their holders have the option to tender certificates to the TOB for redemption at par at each reset date. The residual interests held by the Fund include the right of the Fund (1) to cause the holders of a proportional share of floating rate certificates to tender their certificates at par, and (2) to transfer a corresponding share of the municipal securities from the TOB to the Fund. At April 30, 2007, the aggregate value of the underlying municipal securities transferred to TOBs was approximately $20,832,000, the related liability for trust certificates was $10,000,000 and the range of interest rates was 3.45% to 4.02%. Financial transactions executed through TOBs generally will underperform the market for fixed rate municipal bonds in a rising interest rate environment, but tend to outperform the market for fixed rate bonds when interest rates decline or remain relatively stable. Should short-term interest rates rise, the Fund's investments in TOB Residuals likely will adversely affect the Fund's investment income -- net and distributions to shareholders. Fluctuations in the market value of municipal securities deposited into the TOB may adversely affect the Fund's net asset value per share. While the Fund's investment policies and restrictions expressly permit investments in inverse floating rate securities such as TOB Residuals, they generally do not allow the Fund to borrow money for purposes of making investments. The Fund's management believes that the Fund's restrictions on borrowings do not apply to the secured borrowings deemed to have occurred for accounting purposes. (d) Income taxes -- It is the Fund's policy to comply with the requirements of the Internal Revenue Code applicable to regulated investment companies and to distribute substantially all of its taxable income to its shareholders. Therefore, no federal income tax provision is required. (e) Security transactions and investment income -- Security transactions are recorded on the dates the transactions are entered into (the trade dates). Realized gains and losses on security transactions are determined on the identified cost basis. Dividend income is recorded on the ex-dividend dates. Interest income is recognized on the accrual basis. The Fund amortizes all premiums and discounts on debt securities. (f) Prepaid registration fees -- Prepaid registration fees are charged to expense as the related shares are issued. (g) Dividends and distributions -- Dividends from net investment income are declared daily and paid monthly. Distributions of capital gains are recorded on the ex-dividend dates. (h) Recent accounting pronouncements -- In July 2006, the Financial Accounting Standards Board ("FASB") issued Interpretation No. 48 ("FIN 48"), "Accounting for Uncertainty in Income Taxes -- an interpretation of FASB Statement No. 109." FIN 48 prescribes the minimum recognition threshold a tax position must meet in connection with accounting for uncertainties in income tax positions taken or expected to be taken by an entity, including mutual funds, before being measured and recognized in the financial statements. Adoption of FIN 48 is required for the last net asset value calculation in the first required financial statement reporting period for fiscal years beginning after December 15, 2006. The impact on the Funds' financial statements, if any, is currently being assessed. BLACKROCK INTERMEDIATE MUNICIPAL FUND APRIL 30, 2007 21 Notes to Financial Statements (continued) In September 2006, "Statement of Financial Accounting Standards No. 157, Fair Value Measurements" ("FAS 157"), was issued and is effective for fiscal years beginning after November 15, 2007. FAS 157 defines fair value, establishes a framework for measuring fair value and expands disclosures about fair value measurements. At this time, management is evaluating the implications of FAS 157 and its impact on the Funds financial statements, if any, has not been determined. In addition, in February 2007, FASB issued "Statement of Financial Accounting Standards No. 159, The Fair Value Option for Financial Assets and Financial Liabilities" ("FAS 159"), which is effective for fiscal years beginning after November 15, 2007. Early adoption is permitted as of the beginning of a fiscal year that begins on or before November 15, 2007, provided the entity also elects to apply the provisions of FAS 157. FAS 159 permits entities to choose to measure many financial instruments and certain other items at fair value that are not currently required to be measured at fair value. FAS 159 also establishes presentation and disclosure requirements designed to facilitate comparisons between entities that choose different measurement attributes for similar types of assets and liabilities. At this time, management is evaluating the implications of FAS 159 and its impact on the Fund's financial statements, if any, has not been determined. 2. Investment Advisory Agreement and Transactions with Affiliates: The Investment Advisory Agreement between the Fund and BlackRock Advisors, LLC (the "Manager"), an indirect, wholly owned subsidiary of BlackRock, Inc., became effective on September 29, 2006. Prior to September 29, 2006, Merrill Lynch Investment Managers, L.P. ("MLIM") was the Fund's manager. The general partner of MLIM is Princeton Services, Inc. ("PSI"), an indirect, wholly owned subsidiary of Merrill Lynch & Co., Inc. ("Merrill Lynch"), which is the limited partner. The Fund has also entered into separate Distribution Agreements and Distribution Plans with FAM Distributors, Inc. ("FAMD") and BlackRock Distributors, Inc. and its affiliates ("BDI") (collectively, the "Distributor"). FAMD is a wholly owned subsidiary of Merrill Lynch Group, Inc., and BDI is an affiliate of BlackRock, Inc. Merrill Lynch and The PNC Financial Services Group, Inc. ("PNC") are the principal owners of BlackRock, Inc. The Manager is responsible for the management of the Fund's portfolio and provides the necessary personnel, facilities, equipment and certain other services necessary to the operations of the Fund. For such services, the Fund pays a monthly fee of .55% of the average daily value of the Fund's net assets. The Manager has agreed to waive .05% of its fee resulting in an annual fee equal to .50% of the average daily net assets of the Fund. For the six months ended April 30, 2007, the Manager earned fees of $496,092, of which $45,099 was waived. In addition, the Manager has entered into a sub-advisory agreement with BlackRock Investment Management, LLC ("BIM"), an affiliate of the Manager, under which the Manager pays BIM for services it provides a fee at an annual rate equal to a percentage of the management fee paid by the Fund to the Manager. In addition, the Manager has agreed to reimburse its management fee by the amount of management fees the Fund pays to the Manager indirectly through its investment in Merrill Lynch Institutional Tax-Exempt Fund. For the six months ended April 30, 2007, the Manager reimbursed the Fund in the amount of $20. Pursuant to the Distribution Plans adopted by the Fund in accordance with Rule 12b-1 under the Investment Company Act of 1940, the Fund pays the Distributor ongoing service and distribution fees. The fees are accrued daily and paid monthly at annual rates based upon the average daily net assets of the shares as follows: - -------------------------------------------------------------------------------- Service Distribution Fee Fee - -------------------------------------------------------------------------------- Investor A ....................................... .25% -- Investor A1 ...................................... .10% -- Investor B ....................................... .20% .10% Investor C ....................................... .25% .75% - -------------------------------------------------------------------------------- Pursuant to sub-agreements with each Distributor, broker dealers, including Merrill Lynch, Pierce, Fenner & Smith Incorporated ("MLPF&S"), a wholly owned subsidiary of Merrill Lynch and an affiliate of each Distributor, provide shareholder servicing and distribution services to the Fund. The ongoing service fee compensates the Distributor and each broker-dealer (including MLPF&S) for providing shareholder servicing to Investor A, Investor A1, Investor B and Investor C shareholders. The ongoing distribution fee compensates each Distributor and MLPF&S for providing shareholder and distribution-related services to Investor B and Investor C shareholders. 22 BLACKROCK INTERMEDIATE MUNICIPAL FUND APRIL 30, 2007 Notes to Financial Statements (continued) For the six months ended April 30, 2007, FAMD and BDI earned underwriting discounts and direct commissions, and MLPF&S and BDI earned dealer concessions on sales of the Fund's Investor A and Investor A1 Shares as follows: - -------------------------------------------------------------------------------- FAMD MLPF&S BDI - -------------------------------------------------------------------------------- Investor A .................................... $ 551 $5,996 -- Investor A1 ................................... -- -- $ 59 - -------------------------------------------------------------------------------- For the six months ended April 30, 2007, MLPF&S received contingent deferred sales charges of $1,080 and $1 relating to transactions in Investor B and Class C Shares, respectively. In addition, MLPF&S received contingent deferred sales charges of $3,145 relating to transactions subject to front-end sales charge waivers in Investor A1 Shares. The Manager maintains a call center, which is responsible for providing certain shareholder services to the Fund, such as responding to shareholder inquiries and processing transactions based upon instructions from shareholders with respect to the subscription and redemption of Fund shares. During the six months ended April 30, 2007, the following amounts have been accrued by the Fund to reimburse the Manager for costs incurred running the call center, which are a component of the transfer agent fees in the accompanying Statement of Operations. - -------------------------------------------------------------------------------- Call Center Fees - -------------------------------------------------------------------------------- Institutional ................................................... $416 Investor A ...................................................... $ 11 Investor A1 ..................................................... $463 Investor B ...................................................... $131 Investor C ...................................................... $ 18 - -------------------------------------------------------------------------------- PFPC Inc., an indirect, wholly owned subsidiary of PNC and an affiliate of the Manager, became the Fund's transfer agent. For the six months ended April 30, 2007, the Fund reimbursed the Manager $1,805 for certain accounting services. Certain officers and/or trustees of the Fund are officers and/or directors of BlackRock, Inc. or its affiliates. 3. Investments: Purchases and sales of investments, excluding short-term securities, for the six months ended April 30, 2007 were $35,727,857 and $24,861,745, respectively. 4. Beneficial Interest Transactions: Net increase (decrease) in net assets derived from beneficial interest transactions was $4,205,170 and $(8,046,361) for the six months ended April 30, 2007 and the year ended October 31, 2006, respectively. Transactions in beneficial interest for each class were as follows: - ------------------------------------------------------------------------------- Institutional Shares for the Six Dollar Months Ended April 30, 2007 Shares Amount - ------------------------------------------------------------------------------- Shares sold ................................ 2,193,453 $ 22,468,329 Shares issued to shareholders in reinvestment of dividends ............. 23,156 237,147 ---------------------------- Total issued ............................... 2,216,609 22,705,476 Shares redeemed ............................ (1,271,224) (13,024,984) ---------------------------- Net increase ............................... 945,385 $ 9,680,492 ============================ - ------------------------------------------------------------------------------- Institutional Shares for the Year Dollar Ended October 31, 2006 Shares Amount - ------------------------------------------------------------------------------- Shares sold ................................ 4,020,988 $ 40,960,524 Shares issued to shareholders in reinvestment of dividends and distributions ........................ 99,237 1,011,100 ---------------------------- Total issued ............................... 4,120,225 41,971,624 Shares redeemed ............................ (4,163,299) (42,438,080) ---------------------------- Net decrease ............................... (43,074) $ (466,456) ============================ - ------------------------------------------------------------------------------- Investor A Shares for the Six Dollar Months Ended April 30, 2007 Shares Amount - ------------------------------------------------------------------------------- Shares sold .................................. 168,354 $ 1,726,394 Shares issued to shareholders in reinvestment of dividends ............... 1,029 10,517 ---------------------------- Total issued ................................. 169,383 1,736,911 Shares redeemed .............................. (1,956) (20,067) ---------------------------- Net increase ................................. 167,427 $ 1,716,844 ============================ - ------------------------------------------------------------------------------- Investor A Shares for the Period Dollar Oct. 2, 2006+ to Oct. 31, 2006 Shares Amount - ------------------------------------------------------------------------------- Shares sold ...................................... 15,604 $ 159,487 Shares redeemed .................................. (7) (67) ---------------------------- Net increase ..................................... 15,597 $ 159,420 ============================ + Commencement of operations. - ------------------------------------------------------------------------------- Investor A1 Shares for the Six Dollar Months Ended April 30, 2007 Shares Amount - ------------------------------------------------------------------------------- Shares sold .................................. 52,643 $ 538,934 Shares issued to shareholders in reinvestment of dividends ............... 69,535 711,786 ---------------------------- Total issued ................................. 122,178 1,250,720 Shares redeemed .............................. (812,469) (8,326,431) ---------------------------- Net decrease ................................. (690,291) $(7,075,711) ============================ BLACKROCK INTERMEDIATE MUNICIPAL FUND APRIL 30, 2007 23 Notes to Financial Statements (concluded) - ------------------------------------------------------------------------------- Investor A1 Shares for the Year Dollar Ended October 31, 2006 Shares Amount - ------------------------------------------------------------------------------- Shares sold ................................ 428,799 $ 4,375,953 Automatic conversion of shares ............. 125,138 1,275,870 Shares issued to shareholders in reinvestment of dividends and distributions .......................... 152,300 1,551,857 Shares issued resulting from conversion of shares ................ 2,403,412 24,544,146 ---------------------------- Total issued ............................... 3,109,649 31,747,826 Shares redeemed ............................ (858,199) (8,752,391) ---------------------------- Net increase ............................... 2,251,450 $ 22,995,435 ============================ - ------------------------------------------------------------------------------- Investor B Shares for the Six Dollar Months Ended April 30, 2007 Shares Amount - ------------------------------------------------------------------------------- Shares sold .................................. 2,247 $ 23,060 Shares issued to shareholders in reinvestment of dividends ............... 8,128 83,242 ---------------------------- Total issued ................................. 10,375 106,302 Shares redeemed .............................. (159,784) (1,637,158) ---------------------------- Net decrease ................................. (149,409) $(1,530,856) ============================ - ------------------------------------------------------------------------------- Investor B Shares for the Year Dollar Ended October 31, 2006 Shares Amount - ------------------------------------------------------------------------------- Shares sold .................................. 51,287 $ 524,293 Shares issued to shareholders in reinvestment of dividends and distributions ............................ 36,382 370,767 ---------------------------- Total issued ................................. 87,669 895,060 ---------------------------- Automatic conversion of shares ............... (125,110) (1,275,870) Shares redeemed .............................. (460,278) (4,695,757) ---------------------------- Total redeemed ............................... (585,388) (5,971,627) ---------------------------- Net decrease ................................. (497,719) $(5,076,567) ============================ - ------------------------------------------------------------------------------- Investor C Shares for the Six Dollar Months Ended April 30, 2007 Shares Amount - ------------------------------------------------------------------------------- Shares sold .................................. 142,958 $ 1,460,644 Shares issued to shareholders in reinvestment of dividends ............... 878 8,977 ---------------------------- Total issued ................................. 143,836 1,469,621 Shares redeemed .............................. (5,382) (55,220) ---------------------------- Net increase ................................. 138,454 $ 1,414,401 ============================ - ------------------------------------------------------------------------------- Investor C Shares for the Period Dollar Oct. 2, 2006+ to Oct. 31, 2006 Shares Amount - ------------------------------------------------------------------------------- Shares sold ...................................... 20,126 $ 205,721 Shares redeemed .................................. (6) (69) ---------------------------- Net increase ..................................... 20,120 $ 205,652 ============================ + Commencement of operations. - ------------------------------------------------------------------------------- Class C Shares for the Period Dollar Nov. 1, 2005 to Aug. 25, 2006+ Shares Amount - ------------------------------------------------------------------------------- Shares sold ................................ 511,348 $ 5,215,735 Shares issued to shareholders in reinvestment of dividends and distributions .......................... 69,597 708,846 ---------------------------- Total issued ............................... 580,945 5,924,581 ---------------------------- Shares redeemed ............................ (708,517) (7,244,280) Shares redeemed resulting from conversion to Investor A1 ........... (2,403,368) (24,544,146) ---------------------------- Total redeemed ............................. (3,111,885) (31,788,426) ---------------------------- Net decrease ............................... (2,530,940) $(25,863,845) ============================ + On August 25, 2006, Class C Shares were converted to Class A Shares (now Investor A1 Shares). 5. Short-Term Borrowings: The Fund, along with certain other funds managed by the Manager and its affiliates, is a party to a $500,000,000 credit agreement with a group of lenders. The Fund may borrow under the credit agreement to fund shareholder redemptions and for other lawful purposes other than for leverage. The Fund may borrow up to the maximum amount allowable under the Fund's current prospectus and statement of additional information, subject to various other legal, regulatory or contractual limits. On November 22, 2006, the credit agreement was renewed for one year under substantially the same terms. The Fund pays a commitment fee of .06% per annum based on the Fund's pro rata share of the unused portion of the credit agreement. Amounts borrowed under the credit agreement bear interest at a rate equal to, at each fund's election, the federal funds rate plus .35% or a base rate as defined in the credit agreement. The Fund did not borrow under the credit agreement during the six months ended April 30, 2007. 6. Capital Loss Carryfoward: On October 31, 2006, the Fund had a net capital loss carryforward of $1,822,627, all of which expires in 2014. This amount will be available to offset like amounts of any future taxable gains. 24 BLACKROCK INTERMEDIATE MUNICIPAL FUND APRIL 30, 2007 BlackRock Funds BlackRock Privacy Principles BlackRock is committed to maintaining the privacy of its current and former fund investors and individual clients (collectively, "Clients") and to safeguarding their non-public personal information. The following information is provided to help you understand what personal information BlackRock collects, how we protect that information and why in certain cases we share such information with select parties. If you are located in a jurisdiction where specific laws, rules or regulations require BlackRock to provide you with additional or different privacy-related rights beyond what is set forth below, then BlackRock will comply with those specific laws, rules or regulations. BlackRock obtains or verifies personal non-public information from and about you from different sources, including the following: (i) information we receive from you or, if applicable, your financial intermediary, on applications, forms or other documents; (ii) information about your transactions with us, our affiliates, or others; (iii) information we receive from a consumer reporting agency; and (iv) from visits to our Web sites. BlackRock does not sell or disclose to non-affiliated third parties any non-public personal information about its Clients, except as permitted by law or as is necessary to respond to regulatory requests or to service Client accounts. These non-affiliated third parties are required to protect the confidentiality and security of this information and to use it only for its intended purpose. We may share information with our affiliates to service your account or to provide you with information about other BlackRock products or services that may be of interest to you. In addition, BlackRock restricts access to non-public personal information about its Clients to those BlackRock employees with a legitimate business need for the information. BlackRock maintains physical, electronic and procedural safeguards that are designed to protect the non-public personal information of its Clients, including procedures relating to the proper storage and disposal of such information. Availability of Additional Information Electronic copies of most financial reports and prospectuses are available on the Fund's Web site or shareholders can sign up for e-mail notifications of quarterly statements, annual and semi-annual reports and prospectuses by enrolling in the Fund's electronic delivery program. To enroll: Shareholders Who Hold Accounts with Investment Advisers, Banks or Brokerages: Please contact your financial advisor. Please note that not all investment advisers, banks or brokerages may offer this service. Shareholders Who Hold Accounts Directly with BlackRock: 1) Access the BlackRock Web site at http://www.blackrock.com/edelivery 2) Select eDelivery under the More Information section 3) Log into your account The Fund will mail only one copy of shareholder documents, including prospectuses, annual and semi-annual reports and proxy statements, to shareholders with multiple accounts at the same address. This practice is commonly called "householding" and it is intended to reduce expenses and eliminate duplicate mailings of shareholder documents. Mailings of your shareholder documents may be householded indefinitely unless you instruct us otherwise. If you do not want the mailing of these documents to be combined with those for other members of your household, please contact the Fund at (800) 441-7762. BLACKROCK INTERMEDIATE MUNICIPAL FUND APRIL 30, 2007 25 BlackRock Funds (concluded) Availability of Additional Information (concluded) Availability of Proxy Voting Policies and Procedures The Fund has delegated proxy voting responsibilities to BlackRock and its affiliates, subject to the general oversight of the Fund's Board of Trustees. A description of the policies and procedures that BlackRock and its affiliates use to determine how to vote proxies relating to portfolio securities is available without charge, upon request, on our Web site at www.blackrock.com, by calling (800) 441-7762, or on the Web site of the Securities and Exchange Commission (the "Commission") at http://www.sec.gov. Availability of Proxy Voting Record Information on how proxies relating to the Fund's voting securities were voted (if any) by the Fund's previous manager during the most recent 12-month period ended June 30 is available, upon request and without charge, on our Web site at www.blackrock.com, by calling (800) 441-7762 or on the Web site of the Commission at http://www.sec.gov. Availability of Quarterly Portfolio Schedule The Fund files its complete schedule of portfolio holdings for the first and third quarters of its fiscal year with the Commission on Form N-Q. The Fund's Forms N-Q are available on the Commission's Web site at http://www.sec.gov and may be reviewed and copied at the Commission's Public Reference Room in Washington, D.C. Information regarding the operation of the Public Reference Room may be obtained by calling (800) SEC-0330. The Fund's Forms N-Q may also be obtained upon request, without charge, by calling (800) 441-7762. Shareholder Privileges Account Information Call us at (800) 441-7762 8:00 AM - 6:00 PM EST to get information about your account balances, recent transactions and share prices. You can also reach us on the Web at www.blackrock.com. Automatic Investment Plans Investor Class shareholders who want to invest regularly can arrange to have $50 or more automatically deducted from their checking or savings account and invested in any of the BlackRock portfolios. Systematic Withdrawal Plans Investor Class shareholders can establish a systematic withdrawal plan and receive periodic payments of $50 or more from their BlackRock portfolios, as long as their account is at least $10,000. Retirement Plans Shareholders may make investments in conjunction with Traditional, Rollover, Roth, Coverdell, Simple IRAs, SEP IRAs and 403(b) Plans. 26 BLACKROCK INTERMEDIATE MUNICIPAL FUND APRIL 30, 2007 A World-Class Mutual Fund Family BlackRock offers a diverse lineup of open-end mutual funds crossing all investment styles and managed by experts in equity, fixed income and tax-exempt investing. Equity Funds BlackRock All-Cap Global Resources Portfolio BlackRock Aurora Portfolio BlackRock Asset Allocation Portfolio+ BlackRock Balanced Capital Fund+ BlackRock Basic Value Fund BlackRock Capital Appreciation Portfolio BlackRock Developing Capital Markets Fund BlackRock Equity Dividend Fund BlackRock EuroFund BlackRock Focus Twenty Fund BlackRock Focus Value Fund BlackRock Fundamental Growth Fund BlackRock Global Allocation Fund+ BlackRock Global Dynamic Equity Fund BlackRock Global Financial Services Fund BlackRock Global Growth Fund BlackRock Global Opportunities Portfolio BlackRock Global Resources Portfolio* BlackRock Global Science & Technology Opportunities Portfolio BlackRock Global SmallCap Fund BlackRock Global Technology Fund BlackRock Healthcare Fund BlackRock Health Sciences Opportunities Portfolio BlackRock Index Equity Portfolio* BlackRock International Fund BlackRock International Index Fund BlackRock International Opportunities Portfolio* BlackRock International Value Fund BlackRock Investment Trust BlackRock Large Cap Core Fund BlackRock Large Cap Growth Fund BlackRock Large Cap Value Fund BlackRock Latin America Fund BlackRock Mid-Cap Growth Equity Portfolio BlackRock Mid-Cap Value Equity Portfolio BlackRock Mid Cap Value Opportunities Fund BlackRock Natural Resources Trust BlackRock Pacific Fund BlackRock Small Cap Core Equity Portfolio BlackRock Small Cap Growth Equity Portfolio BlackRock Small Cap Growth Fund II BlackRock Small Cap Index Fund BlackRock Small Cap Value Equity Portfolio* BlackRock Small/Mid-Cap Growth Portfolio BlackRock S&P 500 Index Fund BlackRock U.S. Opportunities Portfolio BlackRock Utilities and Telecommunications Fund BlackRock Value Opportunities Fund Fixed Income Funds BlackRock Bond Fund BlackRock Commodity Strategies Fund BlackRock Enhanced Income Portfolio BlackRock GNMA Portfolio BlackRock Government Income Portfolio BlackRock High Income Fund BlackRock High Yield Bond Portfolio BlackRock Inflation Protected Bond Portfolio BlackRock Intermediate Bond Portfolio II BlackRock Intermediate Government Bond Portfolio BlackRock International Bond Portfolio BlackRock Low Duration Bond Portfolio BlackRock Managed Income Portfolio BlackRock Short-Term Bond Fund BlackRock Total Return Portfolio BlackRock Total Return Portfolio II BlackRock World Income Fund Municipal Bond Funds BlackRock AMT-Free Municipal Bond Portfolio BlackRock California Insured Municipal Bond Fund BlackRock Delaware Municipal Bond Portfolio BlackRock Florida Municipal Bond Fund BlackRock High Yield Municipal Fund BlackRock Intermediate Municipal Fund BlackRock Kentucky Municipal Bond Portfolio BlackRock Municipal Insured Fund BlackRock National Municipal Fund BlackRock New Jersey Municipal Bond Fund BlackRock New York Municipal Bond Fund BlackRock Ohio Municipal Bond Portfolio BlackRock Pennsylvania Municipal Bond Fund BlackRock Short-Term Municipal Fund Target Risk & Target Date Funds BlackRock Prepared Portfolios Conservative Prepared Portfolio Moderate Prepared Portfolio Growth Prepared Portfolio Aggressive Growth Prepared Portfolio BlackRock Lifecycle Prepared Portfolios Prepared Portfolio 2010 Prepared Portfolio 2015 Prepared Portfolio 2020 Prepared Portfolio 2025 Prepared Portfolio 2030 Prepared Portfolio 2035 Prepared Portfolio 2040 Prepared Portfolio 2045 Prepared Portfolio 2050 * See the prospectus for information on specific limitations on investments in the fund. + Mixed asset fund. BlackRock mutual funds are distributed by BlackRock Distributors, Inc. and certain funds are also distributed by FAM Distributors, Inc. You should consider the investment objectives, risks, charges and expenses of the funds under consideration carefully before investing. Each fund's prospectus contains this and other information and is available at www.blackrock.com or by calling 800-882-0052 or from your financial advisor. The prospectus should be read carefully before investing. BLACKROCK INTERMEDIATE MUNICIPAL FUND APRIL 30, 2007 27 This report is transmitted to shareholders only. It is not authorized for use as an offer of sale or a solicitation of an offer to buy shares of the Fund unless accompanied or preceded by the Fund's current prospectus. Past performance results shown in this report should not be considered a representation of future performance. Investment returns and principal value of shares will fluctuate so that shares, when redeemed, may be worth more or less than their original cost. Statements and other information herein are as dated and are subject to change. BlackRock Intermediate Municipal Fund Of BlackRock Municipal Series Trust P.O. Box 9011 Princeton, NJ 08543-9011 BLACKROCK #10437-4/07 Item 2 - Code of Ethics - Not Applicable to this semi-annual report Item 3 - Audit Committee Financial Expert - Not Applicable to this semi-annual report Item 4 - Principal Accountant Fees and Services - Not Applicable to this semi-annual report Item 5 - Audit Committee of Listed Registrants - Not Applicable Item 6 - Schedule of Investments - The registrant's Schedule of Investments is included as part of the Report to Stockholders filed under Item 1 of this form. Item 7 - Disclosure of Proxy Voting Policies and Procedures for Closed-End Management Investment Companies - Not Applicable Item 8 - Portfolio Managers of Closed-End Management Investment Companies - Not Applicable Item 9 - Purchases of Equity Securities by Closed-End Management Investment Company and Affiliated Purchasers - Not Applicable Item 10 - Submission of Matters to a Vote of Security Holders - The registrant's Nominating Committee will consider nominees to the Board recommended by shareholders when a vacancy becomes available. Shareholders who wish to recommend a nominee should send nominations which include biographical information and set forth the qualifications of the proposed nominee to the registrant's Secretary. There have been no material changes to these procedures. Item 11 - Controls and Procedures 11(a) - The registrant's principal executive and principal financial officers or persons performing similar functions have concluded that the registrant's disclosure controls and procedures (as defined in Rule 30a-3(c) under the Investment Company Act of 1940, as amended (the "1940 Act")) are effective as of a date within 90 days of the filing of this report based on the evaluation of these controls and procedures required by Rule 30a-3(b) under the 1940 Act and Rule 15d-15(b) under the Securities and Exchange Act of 1934, as amended. 11(b) - There were no changes in the registrant's internal control over financial reporting (as defined in Rule 30a-3(d) under the Act (17 CFR 270.30a-3(d)) that occurred during the second fiscal quarter of the period covered by this report that have materially affected, or are reasonably likely to materially affect, the registrant's internal control over financial reporting. Item 12 - Exhibits attached hereto 12(a)(1) - Code of Ethics - Not Applicable to this semi-annual report 12(a)(2) - Certifications - Attached hereto 12(a)(3) - Not Applicable 12(b) - Certifications - Attached hereto Pursuant to the requirements of the Securities Exchange Act of 1934 and the Investment Company Act of 1940, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized. BlackRock Intermediate Municipal Fund of BlackRock Municipal Series Trust By: /s/ Robert C. Doll, Jr. ----------------------------------- Robert C. Doll, Jr., Chief Executive Officer of BlackRock Intermediate Municipal Fund of BlackRock Municipal Series Trust Date: June 19, 2007 Pursuant to the requirements of the Securities Exchange Act of 1934 and the Investment Company Act of 1940, this report has been signed below by the following persons on behalf of the registrant and in the capacities and on the dates indicated. By: /s/ Robert C. Doll, Jr. ----------------------------------- Robert C. Doll, Jr., Chief Executive Officer of BlackRock Intermediate Municipal Fund of BlackRock Municipal Series Trust Date: June 19, 2007 By: /s/ Donald C. Burke ----------------------------------- Donald C. Burke, Chief Financial Officer of BlackRock Intermediate Municipal Fund of BlackRock Municipal Series Trust Date: June 19, 2007