The top regulator for Fannie Mae and Freddie Mac is expected to announce millions of dollars in pay packages for top executives at the government-run mortgage-finance titans, people familiar with the matter said.

The Federal Housing Finance Agency approved compensation plans for Fannie Chief Executive Michael Williams and Freddie CEO Charles Haldeman Jr. Those packages are expected to be in a range of $4 million to $6 million, people familiar with the matter said. The companies are expected to spell out pay details for their...