After being absent for about 10 years, Fannie Mae and Freddie Mac will re-enter the low-income housing tax credit market to support affordable rental housing, the Federal Housing Finance Agency announced late this week. But the GSEs’ market share will be capped so they’re not in direct competition with the private market, and their investments must meet certain requirements. Fannie and Freddie will have an annual investment limit of $500 million, which translates to less than a 5 percent market share for each, according to the FHFA. Moreover, any investments more than $300 million during any year must be in areas that have been identified by the FHFA as markets that have difficulty attracting investors.