*

Palantir ( PLTR ) slides despite estimate-topping Q4 revenue

forecast

*

Uber ( UBER ) slides as Q4 adjusted core profit misses estimates

*

Advanced Micro Devices ( AMD ), Super Micro Computer ( SMCI ) results

expected

shortly

(Updates to market close)

By Stephen Culp

NEW YORK, Nov 4 (Reuters) - U.S. stocks closed sharply

lower on Tuesday as big banks warned that equity markets could

be headed for a drawdown, reflecting mounting concerns over

stretched valuations.

All three major U.S. stock indexes slid well into negative

territory after the CEOs of Morgan Stanley ( MS ) and Goldman

Sachs ( GS ) stoked fears of a potential market bubble, with the

S&P 500 having climbed to a series of all-time highs, largely

powered by the artificial intelligence boom.

Tech shares weighed particularly heavily on the

Nasdaq, with AI-related momentum stocks providing the most drag.

JPMorgan Chase ( JPM ) CEO Jamie Dimon warned last month of the

heightened risk of a significant stock market correction within

the next six months to two years, citing factors including

geopolitical tensions.

"Investors seem a little more worried about valuation than they

have in a while, at least today," said Chuck Carlson, chief

executive officer at Horizon Investment Services in Hammond,

Indiana.

"A lot of these companies' valuations were pretty stretched

and their earnings were good, but not great," Carlson added.

"And that's a recipe for profit-taking."

The U.S. government shutdown, the result of a congressional

impasse, is nearing the record for the longest ever. The

resulting dearth of official government data has led to

increased scrutiny of private sources such as ADP's National

Employment report expected Wednesday.

Comments from Federal Reserve officials are being parsed for

clues as to how the data-dependent central bank will forge its

monetary policy in the absence of crucial economic indicators.

Local elections for New York's mayor and governors in New

Jersey and Virginia will also be closely tracked.

According to preliminary data, the S&P 500 lost 80.22

points, or 1.17%, to end at 6,772.40 points, while the Nasdaq

Composite lost 486.09 points, or 2.04%, to 23,348.64.

The Dow Jones Industrial Average fell 252.95 points, or

0.53%, to 47,084.99.

Palantir Technologies ( PLTR ) slid despite the data analytics

company's better-than-expected fourth-quarter revenue forecast.

Uber ( UBER ) fell in the wake of the ride-hailing platform's

quarterly profit miss, while Henry Schein

advanced after hiking its annual profit forecast.

Spotify ( SPOT ) and U.S.-listed shares of Shopify ( SHOP )

both lost ground after their quarterly results.