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    * Wells Fargo, Citigroup among biggest drags on S&P 500
    * Exxon Mobil regulatory probe weighs on S&P, energy sector 
    * U.S. retail sales fall again in December
    * Indexes fall: Dow 0.57%, S&P 0.72%, Nasdaq 0.87%

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    By Echo Wang
    NEW YORK, Jan 15 (Reuters) - Wall Street's main indexes
finished lower on Friday, weighed down by big U.S. banks after
their earnings reports, while the energy fell sharply due to a
regulatory probe into Exxon Mobil Corp  XOM.N .
    The S&P 500 banks index  .SPXBK  lost ground as shares of
Wells Fargo & Co  WFC.N , JPMorgan Chase & Co  JPM.N  and
Citigroup Inc  C.N  tumbled even though they had posted
better-than-expected fourth-quarter profits. The bank sector had
rallied sharply in recent days.  urn:newsml:reuters.com:*:nL4N2JQ2PN
    Wells Fargo, down 7.8%, was among the biggest drags on the
S&P 500, along with Exxon Mobil, down 4.8%.
    "Financials and energy have been disappointing ... that's
bringing down the whole market," said Chris Zaccarelli, chief
investment officer at Independent Advisor Alliance in Charlotte,
North Carolina. 
    "This year is the year for financials, energy, materials,
industrials. So if there is a day when they're not leading, it's
not good news for the market."
    Wall Street's major indexes had recently hit record highs on
hopes for a hefty fiscal stimulus package. 
    Incoming U.S. President Joe Biden late on Thursday unveiled
a $1.9 trillion stimulus proposal, which included some $1
trillion in direct relief to households.  urn:newsml:reuters.com:*:nL1N2JP30B 
    Meanwhile, data showed a further decline in U.S. retail
sales in December in the latest sign the economy lost
considerable speed at the end of 2020. urn:newsml:reuters.com:*:nL1N2JP2H6
    "The weaker-than-expected economic data, and especially in
parts of the economy like retail sales, is a big driver," said
Liz Ann Sonders, chief investment strategist at Charles Schwab.
    "We are seeing sentiment through last week in extreme
speculative frothy euphoric optimistic territory," she said.
"Sometimes it doesn't need a catalyst before it begins to fall
on its own weight."
    The Dow Jones Industrial Average  .DJI  fell 177.26 points,
or 0.57%, to 30,814.26, the S&P 500  .SPX  lost 27.29 points, or
0.72%, to 3,768.25 and the Nasdaq Composite  .IXIC  dropped
114.14 points, or 0.87%, to 12,998.50.
    For the week the S&P 500 and the Nasdaq fell around 1.5%
while the Dow lost 0.91%.
    Earnings for S&P 500 companies are expected to decline 9.5%
in the final quarter of 2020 from a year ago, but are expected
to rebound in 2021, with a gain of 16.4% projected for the first
quarter, according to IBES data from Refinitiv. urn:newsml:reuters.com:*:nL1N2JO21D
    Exxon shares fell after a report said that the U.S.
Securities and Exchange Commission launched an investigation of
the oil major, following a whistleblower's complaint that it
overvalued a key asset in the prolific Permian shale oil basin.
 urn:newsml:reuters.com:*:nL4N2JQ2ZM
    Declining issues outnumbered advancing ones on the NYSE by a
2.20-to-1 ratio; on Nasdaq, a 2.24-to-1 ratio favored decliners.
    The S&P 500 posted 10 new 52-week highs and no new lows; the
Nasdaq Composite recorded 169 new highs and seven new lows.  
    On U.S. exchanges, 14.12 billion shares changed hands on
Friday compared with the 12.76 billion average for the last 20
sessions. 

 (Additional Reporting by Devik Jain and Medha Singh in
Bengaluru and Sinéad Carew, Editing by Marguerita Choy)
 ((E.wang@thomsonreuters.com))