S.G. Warburg Securities has downgraded Fannie Mae's stock to "hold" from "buy."
Tuesday's report bv analyst Francis X. Suozzo cited perceptions among investors of increased political risk to Fannie.
Mr. Suozzo said investors fear that plans to impose regulation on the Student Loan Marketing Association, known as Sallie Mae, might serve as a precedent for changes at Fannie Mae, formally the Federal National Mortgage Association.
Other analysts disagree.
"In general, I don't see the linkage" between Sallie and Fannie, said Peter Treadway, a managing director at Smith Barney & Co. He continues to advise investors to buy Fannie.
And Bruce Harting of Salomon Brothers, who is also maintaining a "buy" rating on Fannie, says the political risk has already affected Fannie Mae's shares and is unlikely to cause further damage.
On Tuesday, Fannie Mae reported second-quarter earnings of $458.8 million, up from $402 million in the quarter last year.