NEW YORK (AP) – In the latest byproduct of the widening global financial crisis, Citigroup Inc. will acquire the banking operations of Wachovia Corp. in a deal facilitated by the Federal Deposit Insurance Corp.

Citigroup will absorb up to $42 billion of losses from Wachovia’s $312 billion loan portfolio, with the FDIC covering any remaining losses, the government agency said Monday. Citigroup also will issue $12 billion in preferred stock and warrants to the FDIC.

The deal greatly expands Citigroup’s retail outlets and secures its place among the U.S. banking industry’s Big Three, along with Bank of America Corp. and J.P. Morgan Chase & Co. But it comes at a cost — Citigroup said Monday it will seek to sell $10 billion in common stock and slashed its quarterly dividend in half to 16 cents to shore up its capital position.

The agreement comes after a fevered weekend courtship in which Citigroup and Wells Fargo & Co. both were reportedly studying the books of Wachovia, which suffers from mounting losses linked to its ill-timed 2006 acquisition of mortgage lender Golden West Financial Corp.

Wachovia, like Washington Mutual Inc., which was seized by the federal government last week, was a big originator of option adjustable-rate mortgages, which offer very low introductory payments and let borrowers defer some interest payments until later years. Delinquencies and defaults on these types of mortgages have skyrocketed in recent months, causing big losses for the banks.

The FDIC asserted Monday that Wachovia did not fail, and that all depositors are protected and there will be no cost to the Deposit Insurance Fund.

Federal Reserve Chairman Ben Bernanke, in a statement Monday, said he supports the “timely actions” taken by the FDIC “which demonstrate our government’s unwavering commitment to financial and economic stability.”

Treasury Secretary Henry Paulson also welcomed the sale of Wachovia to Citigroup, saying it would “mitigate potential market disruptions.” Paulson said he agreed with the FDIC and the Fed that a “failure of Wachovia would have posed a systemic risk” to the nation’s financial system.

“As I have said before, in this period of market stress, we are committed to taking all actions necessary to protect our financial system and our economy,” Paulson said.

As details of its takeover unfolded, Wachovia shares plunged 91 percent to 94 cents. The stock had closed Friday at $10, down 74 percent for the year.

Now that a deal for Wachovia is complete, the most troubled of the nation’s largest financial institutions have been dealt with. However, the FDIC estimated there were 117 banks and thrifts in trouble during the second quarter, the highest level since 2003. And that number is likely to have increased during the third quarter.

With the acquisition of Wachovia, Citigroup has reclaimed its title as the biggest U.S. bank by total assets. Including Wachovia, the bank now has assets of $2.91 trillion, as of June 30. That could change, however, as Citigroup shrinks its balance sheet, a decision Chief Executive Vikram Pandit made in May to rid the bank’s books of risky debt.

In terms of current market capitalization, Bank of America Corp. remains the largest U.S. bank, followed by JPMorgan Chase & Co. in second and Citigroup in third place.

Just a short time ago, Citigroup was under the scrutiny of investors who worried about the possibility of its collapse given its massive exposure to mortgage-backed securities. The New York-based bank has not turned a profit for three straight quarters, and lost a total of $17.4 billion during that period after writing down its assets by about $46 billion. That’s the most write-downs of any U.S. bank.

But the government’s proposed $700 billion bailout plan could prove to be the deal’s silver lining.

While the plan broadly aims to prevent banks from profiting on the sale of troubled assets to the government, there is an exception made for assets acquired in a merger or buyout, or from companies that have filed for bankruptcy.

This detail could allow Citigroup to sell toxic mortgages and other assets it gained from Wachovia for a higher price than the bank actually paid for them.

The Wachovia deal caps a wave of unprecedented upheaval in the financial sector in the past six months that has redefined the banking industry, starting with the government-led forced sale of Bear Stearns Cos. to JPMorgan in March.

The failure of IndyMac Bancorp in July reignited investors’ fears about the stability of the financial sector, which led to the eventual takeover of struggling mortgage lenders Fannie Mae and Freddie Mac.

Earlier this month, officials seized both Fannie and Freddie, temporarily putting them in a government conservatorship, replacing their chief executives and taking a financial stake in the mortgage finance companies.

After U.S. regulators made it clear that they would not bail out struggling investment bank Lehman Brothers Holdings Inc., rival Merrill Lynch & Co. arranged a hasty deal to be bought by Bank of America Corp. for $50 billion in stock.

Lehman Brothers was subsequently forced to declare bankruptcy, the largest ever in the United States. Investor concerns quickly turned to American International Group Inc., the nation’s largest insurer. Staving off a failure that could have sent shock waves throughout the global markets, the federal government injected an $85 billion emergency loan into the insurer.

Just days later, the government seized Seattle-based Washington Mutual, marking the largest bank failure in U.S. history. WaMu’s deposits and assets were acquired by JPMorgan for $1.9 billion.

These events have now culminated in extraordinary moves by the federal government to try to fix the financial crisis that began more than a year ago. Lawmakers are to vote Monday on an unpopular $700 billion plan to rescue troubled financial companies.

Wachovia’s problems stem largely from its acquisition of mortgage lender Golden West Financial Corp. in 2006 for roughly $25 billion at the height of the nation’s housing boom. With that purchase, Wachovia inherited a deteriorating $122 billion portfolio of Pick-A-Payment loans, Golden West’s specialty, which let borrowers skip some payments.

This summer, Wachovia reported a $9.11 billion loss for the second quarter, announced plans to cut 11,350 jobs — mostly in its mortgage business — and slashed its dividend. Wachovia also boosted its provision for loan losses to $5.57 billion during the second quarter, up from $179 million in the year-ago period.