CHARLOTTE, N.C. (AP) -- Wachovia Corp., the nation's fourth-largest bank, named Treasury Undersecretary Robert Steel chief executive on Wednesday, ending a nearly six-week search for a new leader.

The Charlotte-based bank also said it has set aside $4.2 billion pretax to cover bad loans for the quarter, leading to an estimated second-quarter loss of about $2.6 billion to $2.8 billion.

The quarterly loss will equal $1.23 to $1.33 per share, excluding an expected write-down of goodwill. Analysts polled by Thomson Financial expected a profit.

Wachovia is expected to release second-quarter earnings on July 22.

Steel succeeds Ken Thompson, who was ousted by the bank's board in June after a series of missteps.

Among them was Thompson's decision to buy mortgage lender Golden West Financial Corp. in 2006 for roughly $25 billion at the height of the nation's housing boom.

Steel, 56, who has been the Treasury Department's liaison with Wall Street since the fall of 2006, announced his resignation Wednesday, effective immediately. He is an alumnus of investment bank Goldman Sachs Group Inc. He is also a Durham, N.C., native and is chairman of the Board of Trustees at Duke University, his alma mater.

Treasury Secretary Henry Paulson praised Steel and said, "I know he will excel in his future endeavors."