Countrywide Financial Corp. reported today that it lost $421.9 million in the fourth quarter as more than one-third of the subprime mortgage borrowers in its servicing portfolio fell behind on payments, Reuters reported. On Jan. 11, Bank of America Corp. agreed to acquire the company for $4.3 billion.

Countrywide’s net losses for the quarter totaled 79 cents per share, compared with a profit of $821.6 million, or $1.01 per share, in the year-ago period. The company projected a fourth-quarter profit of 25 to 75 cents per share on Oct. 26, and did not update its forecast amid a housing market downturn.

Its third-quarter loss of $1.2 billion was the company’s first quarterly loss in 25 years. For the entire year, Countrywide lost $704 million, or $2.03 per share.

In the fourth quarter, Countrywide wrote down $831 million, primarily related to prime home equity loans, set aside $907 million for credit losses and took $87 million in restructuring charges.

Countrywide also faces numerous investigations into its lending practices, which critics say were overly bold and fueled a housing and credit crisis, and lawsuits from shareholders and borrowers. The U.S. Securities and Exchange Commission is looking into CEO Angelo Mozilo’s stock sales. Mozilo announced yesterday that he would give up $37.5 million of severance and other perks he would have gained from Bank of America’s acquisition.