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* Microsoft up as ousted OpenAI CEO set to join company

* Bristol Myers down as Bayer's anti-clotting drug trial fails

* Futures: Dow down 0.05%, S&P down 0.02%, Nasdaq up 0.04%

Nov 20 (Reuters) -

Wall Street was poised for a subdued open on Monday as investors awaited more clues on when the Federal Reserve might begin cutting interest rates, while Microsoft gained on news that former OpenAI head Sam Altman will join the software giant.

Microsoft's shares advanced nearly 1% before the bell after CEO Satya Nadella said Altman is set to join the company to lead a new advanced AI research team.

Other megacap stocks were mixed, with Nvidia edging 0.8% higher, while Alphabet slipped 1.0%.

The three main U.S. stock indexes have staged a stellar rebound in November, posting gains for the third week in a row on Friday as evidence of easing U.S. inflation supported bets that the Fed was done raising interest rates.

The benchmark S&P 500 is now only 2% away from its highest level this year reached in July.

"(The rally) is well overdone because we had a very swift move on the idea that they (the Fed) are going to cut interest rates," said Ken Polcari, managing partner at Kace Capital Advisors.

"You'll see some consolidation in the market over the next couple of weeks before we get that typical year end seasonal Santa rally."

Traders have nearly fully priced in the likelihood that the Fed will keep interest rates unchanged in December, and have started pricing in rate cuts as soon as March, according to the CME Group's FedWatch tool.

A number of catalysts will set the tone for equities this week, with thin trading volumes ahead of the Thanksgiving holiday also affecting market moves.

Chip designer Nvidia is due to report quarterly results on Tuesday, wrapping up the third-quarter earnings season for the "Magnificent Seven" group of megacap companies.

The Fed is expected to issue minutes of its November meeting on Tuesday, which will be parsed for clues on the direction of U.S. interest rates. Black Friday sales will provide a gauge on the state of U.S. consumer spending.

At 8:21 a.m. ET, Dow e-minis were down 17 points, or 0.05%, S&P 500 e-minis were down 1 points, or 0.02%, and Nasdaq 100 e-minis were up 5.75 points, or 0.04%.

Among other movers,

Bristol Myers Squibb

fell 4.5% premarket as Germany's Bayer on Sunday stopped a late-stage trial testing a new anti-clotting drug, hurting investor confidence in all firms developing similar class of drugs.

Equipment rental company

United Rentals

slipped 4.4% after a bleak profit forecast from Britain's Ashtead Group.

(Reporting by Amruta Khandekar and Shristi Achar A; Editing by Maju Samuel)