US STOCKS-S&P 500 ends a hair lower; hedge fund default concerns hit banks

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* Boeing rises on Southwest order for 737 MAX jets
* Bank stocks fall after default by fund manager
* Indexes: Dow up 0.3%, S&P 500 down 0.09%, Nasdaq down 0.6%

(Adds market details after the close, including volume)
By Caroline Valetkevitch
NEW YORK, March 29 (Reuters) - The S&P 500 ended just
slightly in the red on Monday, with bank shares falling amid
warnings of potential losses from a hedge fund's default on
margin calls, while optimism over the economy limited the day's
declines.
The Dow ended higher, with shares of planemaker Boeing Co
BA.N rising 2.3% after the company reached a deal with U.S.
budget carrier Southwest Airlines Co LUV.N for a variant of
the 737 MAX aircraft. Nomura 8604.T and Credit Suisse CSGN.S are facing
billions of dollars in losses after a U.S. hedge fund, named by
sources as Archegos Capital, defaulted on margin calls, putting
investors on edge about who else might have been caught out.
Shares of big U.S. banks and even regional banks fell on the
news. The KBW Nasdaq Bank stock index .BKX ended 2.3% lower
after falling nearly 3.5% during the session. "There's still chatter as to whether or not, and which,
American banks may be affected. That is a question that's
lurking. But so far the market has taken (the news) in stride
essentially," said Quincy Krosby, chief market strategist at
Prudential Financial in Newark, New Jersey.
Indexes ended off their lowest levels of the day. Optimism
about speedy vaccinations and record stimulus, which drove the
Dow and the S&P 500 to record closing highs last week, helped
keep a floor in the market along with upbeat estimates for
upcoming earnings, she said.
The Dow Jones Industrial Average .DJI rose 98.49 points,
or 0.3%, to 33,171.37, the S&P 500 .SPX lost 3.45 points, or
0.09%, to 3,971.09 and the Nasdaq Composite .IXIC dropped
79.08 points, or 0.6%, to 13,059.65.
Discovery Inc DISCA.O , ViacomCBS VIAC.O , U.S.-listed
shares of Baidu BIDU.O and VIPShop VIPS.N , all linked to
Archegos, fell, extending recent losses.
The Nasdaq was on track to post its first monthly decline in
five months.
Investors may also be adjusting their holdings for
quarter-end "window dressing," Krosby said.
Volume on U.S. exchanges was 11.02 billion shares, compared
with the 13.6 billion average for the full session over the last
20 trading days.
Declining issues outnumbered advancing ones on the NYSE by a
1.93-to-1 ratio; on Nasdaq, a 3.12-to-1 ratio favored decliners.
The S&P 500 posted 71 new 52-week highs and no new lows; the
Nasdaq Composite recorded 88 new highs and 54 new lows.