NEW YORK (Reuters) - Wachovia Corp., the No. 4 U.S. bank, is near an agreement to buy Golden West Financial Corp. for about $26 billion, giving it its first significant exposure to the fast-growing western United States, The Wall Street Journal said in its online edition Sunday.

Final details are being worked out, the newspaper said, citing unnamed people familiar with the matter.

About three-quarters of the price will be paid in stock and one-quarter in cash, the newspaper said. Preparations are being complicated by a Wachovia-hosted professional golf tournament in its Charlotte, North Carolina, hometown.

The New York Times in its online edition said the transaction should be announced on Monday, citing unnamed people involved in the negotiations. Wachovia's board approved the purchase this afternoon during the golf tournament, while Golden West's board is to meet Sunday night, it said.

Calls to both companies were not immediately returned.

Adding Oakland, California,-based Golden West, the No. 2 U.S. savings and loan, would substantially raise Wachovia's exposure to the mortgage industry, which most experts expect to slow as interest rates rise.

Golden West operates World Savings Bank, and has 283 savings branches in 10 U.S. states, but is best known as an adjustable-rate mortgage lender. It has lending operations in 39 states.

A merger would also cap the careers of Herbert and Marion Sandler, Golden West's co-chairmen and co-chief executives. The husband and wife founded the thrift in 1963, and are now in their mid-70s.

Golden West's market capitalization is about $21.75 billion, based on reported shares outstanding and Friday's closing price of $70.51.

Wachovia (Research) Chief Executive Ken Thompson has built his bank through several mergers, most recently the 2004 acquisition of SouthTrust Corp. He created the current bank when First Union Corp. bought Wachovia in 2001 and took its name.

Though analysts have accused Thompson, like his Charlotte counterpart Kenneth Lewis at Bank of America Corp. (Research), of overpaying for acquisitions, analysts have said the integrations of the old Wachovia and of SouthTrust have gone well.

Wachovia largely operates in the eastern and southern United States.

Adding Golden West (Research) would markedly increase Wachovia's presence in California, which it entered on March 1 when it acquired Westcorp Inc. and its WFS Financial Inc. unit. Wachovia has said it wants to expand in the most populous U.S. state.

Golden West last month said first-quarter profit rose 12 percent to $390.9 million, or $1.25 per share.

Of the $11.6 billion of loans it originated, 99 percent were adjustable-rate mortgages, which can offer homeowners lower initial monthly payments than fixed-rate mortgages.

As of March 31, Golden West had $127.6 billion of assets, and Wachovia had $541.8 billion.

A combined company would rank well behind No. 3 U.S. bank JPMorgan Chase & Co. (Research) in size, but further ahead of No. 5 Wells Fargo & Co. (Research)