* Weak global manufacturing data sinks stocks
* U.S. in recession for past year, according to NBER
* Oil trades near $50 a barrel
* U.S. 10-year Treasury yield at 50-year low
By Daniel Bases
NEW YORK, Dec 1 (Reuters) - A spate of grim manufacturing reports on Monday showing a global economic slowdown sent stock markets in both the United States and Europe down 6 percent, as investors piled into the safe haven of U.S. government bonds, driving their yields to at least 50-year lows.
Crude oil prices slumped about 8 percent to around $50 as OPEC deferred a decision to cut supply, driving down energy shares on both sides of the Atlantic.
The National Bureau of Economic Research, regarded as the arbiter of U.S. recessions, made official the U.S. economy slipped into recession in December 2007, ending a 73-month economic expansion.
Manufacturing data from China, Europe and America illustrated the impact of economic decline, with a U.S. manufacturing index falling to a 26-year low in November.
"Things are looking quite bleak. Everyone acknowledges that," said Brian Gendreau, investment strategist at ING Investment Management in New York. "The question is to what extent is that already priced into the markets. Apparently, not entirely."
The U.S. dollar rallied on a combination of safe-haven flows and hopes that a substantial economic stimulus package will bolster economic activity. The Japanese currency gained ground as investors reversed risky trades funded by cheap yen.
"Until we're through the deterioration in the data then the likelihood is that risk aversion will remain elevated and we'll see renewed interest in lower-yielding currencies," said Derek Halpenny, European head of global currency research at BTM UFJ.
U.S. stocks slid on signs of the deepening global economic slump, puncturing last week's market enthusiasm, with financial services companies and retailers among Wall Street's biggest casualties.
Major industrial companies also contributed to losses on signs global demand is faltering.
Shortly after 1 p.m., the Dow Jones industrial average <
> was down 415.92 points, or 4.71 percent, at 8,413.12. The Standard & Poor's 500 Index <.SPX> was down 50.69 points, or 5.66 percent, at 845.55. The Nasdaq Composite Index < > was down 91.48 points, or 5.96 percent, at 1,444.09.With the holiday shopping season under way, investors fear that retailers may turn in their bleakest sales in perhaps two decades. The S&P retail index <.RLX> declined 7.1 percent, as shares of department store operator Macy's Inc <M.N> tumbled 11.7 percent to $6.55.
Shares of Wal-Mart Stores <WMT.N>, the world's biggest retailer and a Dow component, shed 4.1 percent to $53.62.
Among financials, shares of Citigroup <C.N> sank 16.5 percent to $6.92 after an influential analyst forecast more losses for the major U.S. bank.
A slide in commodity prices pushed resource stocks into the red, with aluminum producer Alcoa <AA.N>, a Dow component, tumbling 10.2 percent to $9.66.
Factory activity in the United States fell to a reading of 36.2 in November from 38.9 in October, the weakest level since 1982, the Institute for Supply Management said. Readings below 50 indicate contraction in activity.
In Europe, The FTSEurofirst 300 index of leading European shares closed down 6.04 percent to 810.04 <
> following a gain of more than 13 percent last week, with banks and mining companies leading the way down.Banks were the worst hit, with Standard Chartered Bank <STAN.L> falling 14 percent and UBS <UBSN.VX> down 12 percent, Fortis <FOR.BR> slipping 11 percent and BNP Paribas <BNPP.PA> declining 7.6 percent.
Miners tracked weaker metals prices. BHP Billiton <BLT.L>, Anglo American <AAL.L>, Vedanta Resources <VED.L>, Lonmin <LMI.L>, Kazakhmys <KAZ.L>, Xstrata <XTA.L>, Antofagasta <ANTO.L> and Rio Tinto <RIO.L> fell between 7 and 18 percent.
The Markit Eurozone Purchasing Managers Index for the manufacturing sector slumped to 35.6 in November, the lowest ever in the survey's 11-year history.
The grim reading reinforced expectations the European Central Bank would cut interest rates later this week to 2.5 percent or even lower.
Interest rate futures are fully pricing in the chance that the ECB would lower the cost of borrowing by 75 basis points on Thursday to 2.50 percent as inflationary pressures ease.
In currencies, the euro <EUR=> was down 0.52 percent at $1.2629 from a previous session close of $1.2695. Against the Japanese yen, the dollar <JPY=> was down 2.45 percent at 93.13 from a previous session close of 95.470.
The yuan also tumbled against the dollar, heading for its biggest daily decline since its peg to the dollar was abolished in July 2005, on speculation China might adjust foreign exchange policy, permitting more yuan weakness, to stimulate its economy.
Benchmark 10-year U.S. Treasuries <US10YT=RR> were up 24/32, with the yield falling to 2.8379 percent.
U.S. light sweet crude oil <CLc1> fell $4.46, or 8.19 percent, to $49.97 per barrel.
Spot gold prices <XAU=> fell $43.00, or 5.27 percent, to $772.50 an ounce.
Tokyo's Nikkei 225 <
> fell 115.05 points or 1.35 percent to 8,397.22.The MSCI world equity index <.MIWD00000PUS> fell 4.82 percent to 209.65, after rising 12.37 percent last week. (Additional reporting by Natsuko Waki, Veronica Brown, Jonathan Cable in London; Chris Reese, John Parry, Gertrude Chavez-Dreyfuss, and Ellis Mnyandu in New York; Editing by Leslie Adler)