Credit card transaction processor First Data Corp. (NYSE:FDC) said that it is being acquired by an affiliate of private equity firm Kohlberg Kravis Roberts & Co. for about $27 billion, which would be among the richest ever private takeover offers in the U.S. The proposed deal comes amid a flurry of activity by buyout groups to take public companies private. KKR has offered $34 a share for First Data, a premium of about 26% over First Data's closing price last Friday.  First Data shares rose $5.55, or 21%, to close at $32.45 Monday on the NYSE after briefly rising to a 52-week high of $32.90. It has about 754 million common shares outstanding which would be worth $25.6 billion at the offered price. In addition, the company said unvested stock options and restricted stock awards that would vest upon a takeover would add about $1.4 billion to what the buyer would pay for First Data stock, boosting the deal's value to about $27 billion.

Real estate mogul Sam Zell won the battle of the billionaires Monday, landing media conglomerate Tribune Co. (NYSE:TRB) after a down-to-the-wire bidding war. Even with the buyout's $8.2 billion price tag, the outlook for the nation's second-largest newspaper publisher remained as uncertain as it did six months ago when it began a strategic review to boost a lagging stock price. A big chunk of new debt also will be required to pay the $34 a share cash buyout. Zell is counting on repaying the debt largely through tax benefits from a new employee stock option plan that would supplement existing retirement accounts for the company's 20,000 workers. Aside from selling the Chicago Cubs baseball team and its stake in Comcast SportsNet, Zell and Tribune executives were mum about prospects for the rest of the company's assets, including 23 television stations and nine newspapers ranging in size from the Los Angeles Times and the Chicago Tribune to the Daily Press in Newport News, Va. that will remain after two papers in Connecticut are sold. The buyout will be conducted as a two-part deal, the company said. The first stage, expected to be completed in the second quarter, will involve a cash tender offer of $34 per share for 126 million shares, more than half of the outstanding Tribune shares. The remaining shares will be purchased later at the same $34 per share price. Tribune has about 240 million shares outstanding, according to a regulatory filing.

New Century Financial Corp. (OTC:NEWC), once the nation's second-largest provider of home loans to high-risk borrowers, filed for bankruptcy protection on Monday, the victim of its own financial missteps as well as pressures felt by its rival lenders. New Century immediately fired 3,200 workers, more than half of its work force, and said it intends to sell off its major assets.

Citibank, the retail banking arm of Citigroup Inc. (NYSE:C), said Monday it's starting a mobile banking service that customers can download to their cell phones. The service, Citi Mobile, will be introduced first in Southern California and should be available throughout the United States by midyear, bank executives told a news conference in New York. Citi joins other U.S. financial institutions that are rolling out wireless banking applications. New York-based Citigroup, the nation's largest financial institution, sees the new service as yet another channel for customers to use for their banking, beyond the Internet bank Citibank Online, automated teller machines and the Citi call center operations.

M&T Bank Corp’s (NYSE:MTB) stock dropped 8.5%, or $9.88, to $105.95, after it said late on Friday that problems in mortgages with limited income documentation would hurt results.

Sun Microsystems (NDAQ:SUNW) shares declined 3.5%, or $0.21, to $5.80 after Sanford C. Bernstein lowered its rating on the company's stock, saying fiscal Q3 results could be disappointing.

US phone company AT&T Inc. (NYSE:T) said it and Mexican cell phone operator America Movil were in talks to buy stakes in the company that controls Telecom Italia for about $6.4 billion. AT&T shares ended up $0.03 at $39.46.

Starwood Hotels & Resorts Worldwide Inc. (NYSE:HOT) rose $2.97, or 4.6%, to $67.82, after announcing Steven J. Heyer has resigned as chief executive and a director after the company's board lost confidence in his leadership. The company also reaffirmed its first-quarter and full-year guidance.

Apple Inc. (NDAQ:AAPL) shares rose $0.74 to $93.65 after it reached an agreement with EMI Group PLC to sell the record label's songs online without copy protection software. However, the deal did not include The Beatles catalog.