British hedge fund Toscafund Asset Management has taken big stakes in the largest savings and loans in the U.S.

The firm, which has suffered double-digit losses due to its investments in financial services companies, reported in separate filings that it owns a 6% stake in Washington Mutual and a 5.1% stake in Sovereign Bancorp. Both banks have been battered by the credit crisis, losing two-thirds and one-half of their market capitalizations, respectively.

Tosca recently raised $800 million in new capital to invest in the financial sector. In April, the firm was part of a group, led by private equity firm TPG, which gave WaMu a $7 billion capital injection, taking a “significant” stake at the time.