JPMorgan Chase said today it will acquire rival Bear Stearns in a deal valued at $236.2 million — or $2 a share — a stunning collapse for one of the world’s largest and most venerable investment banks.

The last-minute buyout was aimed at averting a Bear Stearns bankruptcy and a spreading crisis of confidence in the global financial system.

The Federal Reserve and the American government swiftly approved the all-stock deal, showing the urgency of completing the deal before world markets opened.

Bear Stearns shares closed Friday at $30 a share. At their peak, the shares traded at $159.36.

The Fed will provide special financing to JPMorgan Chase for the deal, JPMorgan Chase said. The central bank has agreed to fund up to $30 billion of Bear Stearns’ less liquid assets. Risky bets on securities tied to subprime mortgages — loans given to customers with poor credit history — crippled Bear Stearns, the nations’ fifth-largest investment bank.

At almost the same time as the deal for control of Bear Stearns was announced, the Federal Reserve said it approved a cut in its lending rate to banks to 3.25% from 3.50% and created another lending facility for big investment banks. The central bank’s official meeting is on Tuesday. Before the emergency move to lower the discount rate, which is the rate at which banks lend each other money, the Fed was widely expected to again cut its headline rate by as much as a full point to 2%.

The announcements from both the Fed and JPMorgan come ahead of what some analysts expected to be a brutal day for global stocks. Already, before the announcements, New Zealand’s markets opened drastically lower — then began to recover after the deal was unveiled.

“This is going to go down in very historic terms,” the chief investment strategist for New York-based Meridian Equity Partners, Peter Dunay, said. “This is about credit being overextended, and how bad it is for major financial institutions and for individuals. This is why we’re probably heading into a recession.”

A collapse of Bear Stearns could have created a further crisis of confidence in world financial markets amid a deepening credit crunch. JPMorgan’s acquisition of Bear Stearns represents roughly 1% of what the investment bank was worth just 16 days ago.

The deal marked a 93.3 percent discount to Bear Stearns’ market capitalization as of Friday, and roughly a 98.8% discount to its book value as of February 29.

“The past week has been an incredibly difficult time for Bear Stearns,” the Bear Stearns Chief Executive, Alan Schwartz, said in a statement. “This represents the best outcome for all of our constituencies based upon the current circumstances.”

Wall Street analysts say the bid to rescue Bear Stearns was more than just saving one of the world’s largest investments bank — it was a prop for the American economy and the global financial system. An outright collapse could cause huge losses for banks, hedge funds, and other investors to which Bear Stearns is connected.

The government, led by the Treasury Department and the Fed, was reported to have closely monitored the talks between JPMorgan and Bear Stearns. The Treasury Secretary, Henry Paulson, also a former chief executive of Goldman Sachs Group Inc., “has been in nearly continuous consultations all weekend,” a Treasury Department spokeswoman, Brookly McLaughlin, said.

After days of denials that it had liquidity problems, Bear was forced into a JPMorgan-led, government-backed bailout on Friday. The arrangement, the first of its kind since the 1930s, resulted in Bear getting a 28-day loan from JPMorgan with the government’s guarantee that JPMorgan would not suffer any losses on the deal.

This is not the first time Bear Stearns has earned a place in Wall Street history. A decade ago, Bear Stearns refused to help bail out a hedge fund that was deemed “too big to fail.” On Friday, the tables had turned, with the now-struggling investment bank in need of the same kind of aid.

Bear Stearns was founded in 1923 and in recent years was best known for its aggressive investing in mortgage-backed securities — and what was once a cash cow turned into the investment bank’s undoing.

In June, two Bear-managed hedge funds worth billions of dollars collapsed. The funds were heavily invested in securities backed by subprime mortgages. Until that point, subprime mortgage-backed securities were immensely popular with investors because of their profitability.

The funds’ collapse and subsequent problems in the credit markets called into question Bear Stearns’ ability to manage its own risk and the leadership ability of then-Chief Executive James Cayne. Critics of the company said Cayne spent too much time away from the office last year playing golf and bridge as the problems unfolded.

Mr. Cayne is the same executive who refused to let Bear Stearns provide support as part of a Federal Reserve-led plan to rescue Long-Term Capital Management in 1998. His reticence was said to deeply anger some of his fellow Wall Street CEOs, and the episode came up every time Bear was reported to be in trouble in recent months.

Mr. Cayne took over from the legendary Alan “Ace” Greenberg in 1993. Mr. Greenberg joined Bear Stearns as a clerk, working his way up through the ranks to eventually take over as CEO in 1978. MR. Greenberg was known for his irreverent style, and his regular memos to employees were turned into a book called “Memos from the Chairman.”

Before Mr. Greenberg’s ascendancy to CEO, Bear Stearns began to expand from its New York roots throughout the 1950s and 1960s, opening international offices and expanding its American operations.

The company was opened in 1923 as an equity trading shop. Today, it has subsidiaries providing a wide array of financial services products for individuals, corporations, institutions, and governments. Generally, it provides capital markets, wealth management, and global clearing services to its customers.