Which agency is known for primarily purchasing conventional mortgage loans?

Freddie Mac is known primarily for purchasing conventional mortgage loans. This government-sponsored enterprise (GSE) was established to promote stability and affordability in the housing market. One of its main functions is to buy and securitize conventional loans, which are loans that conform to certain guidelines set by the GSEs. By purchasing these loans from lenders, Freddie Mac provides lenders with liquidity and helps facilitate the availability of mortgage credit to consumers.

In the context of the other agencies:

Ginnie Mae primarily deals with government-insured loans, such as those backed by the Federal Housing Administration (FHA) and the Veterans Affairs (VA) program, rather than conventional loans. Farmer Mac focuses on providing financing for agricultural and rural housing loans, staying within the agricultural sector rather than conventional mortgage lending. Fannie Mae, while also engaged in the buying of conventional loans, operates in a similar space to Freddie Mac, but the distinction is that Freddie Mac’s primary role emphasizes the conventional loan market more directly.

Thus, Freddie Mac's specific focus on purchasing and securitizing conventional loans makes it the correct choice for the question.