MFS High Yield Municipal Trust operates as a nondiversified, closed-end management investment company. The trust invests primarily in medium and lower quality bonds and notes issued by or on behalf of state and local government units. Its portfolio primarily comprises investments in health care, tax-backed, utilities, transportation, housing, education, industrials, resource recovery, industrial, manufacturing, oil and gas, and refunded/escrowed sectors. Columbia Management Advisors, Inc. serves as the investment advisor of the trust. The trust was formerly known as Colonial Municipal Income Trust and changed its name to MFS High Yield Municipal Trust in 2007. MFS High Yield Municipal Trust was founded in 1987 and is based in Boston, Massachusetts.