NPR News

Michael J. Williams said he is stepping down as chief executive of the quasi-governmental mortgage giant Fannie Mae. The company made the announcement late last night, saying Williams will wait to step down until the board of directors names a successor.

"I decided the time is right to turn over the reins to a new leader," Williams said in a statement.

Twinkies maker Hostess Brands Inc., is again seeking protection from its creditors, filing for Chapter 11 bankruptcy as the company tries to cope with high debt and rising costs of labor and raw materials.

Hostess, which also makes Ho Hos, Sno Balls, and Wonder Bread, is a privately held company based in Irving, Tex. It owes millions to suppliers and labor unions. The company has reportedly found some financing to keep it running during bankruptcy proceedings.

For our Newscast desk, Larry Abramson reports:

Pakistani officials say the United States launched a drone strike early Wednesday morning for the first time since November. The AP says the drone strike killed four in North Waziristan, which is close to the Afghan border and has been a hot spot for U.S. strikes.

An Iranian nuclear scientists was killed by a car bomb in Tehran this morning, Iran's official news agency said. According to Press TV, Iran's English-language outlet, a magnetic bomb was placed beneath Mostafa Ahmadi Roshan's car by a man in a motorcycle.

Press TV says Roshan and his driver were killed and a bystander was injured. Roshan was a "chemical engineering graduate and served as marketing deputy of Iran's Natanz nuclear facility."