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* Federal Reserve rate verdict due at 2 p.m. ET

* Coty gains on raising sales forecast

* Pinterest gains on Citigroup upgrade, share buyback

* Indexes mixed: Dow up 0.55%, S&P up 0.18%, Nasdaq down 0.18%

Sept 20 (Reuters) - The S&P 500 and the Dow gained on Wednesday as Treasury yields pulled back ahead of a likely pause in the Federal Reserve's policy tightening campaign, though concerns over rates staying higher for longer kept investor sentiment in check.

The U.S. central bank is expected to maintain its key rate in the range of 5.25%-5.50% as it concludes its meeting at 2 p.m. ET, with investors focused on Fed economic projections and Chair Jerome Powell's comments for clues on the outlook for rates and inflation.

Recent economic data has signaled an easing in core inflation, fuelling bets interest rates could have peaked, but a surge in oil prices has clouded the outlook for headline inflation, providing the Fed room to keep rates higher for longer. Reinforcing the likelihood of a Fed pause, U.S. Treasury yields retreated from their 2007 highs hit in the previous session.

However, megacap growth stocks including Alphabet, Microsoft and Apple lost between 0.7% and 1.6%, weighing on the communication services and information technology sectors. The tech-heavy Nasdaq also gave up its early gains.

"Concerns remain that the Fed is clearly holding policy at what would be considered to be a restrictive level," said Mark Luschini, chief investment strategist at Janney Montgomery Scott.

"Everybody is watching for any kind of evidence that would suggest that the traction from tight monetary policy is inflicting damage on the economy."

Financial markets have priced in a 99% chance the Fed will pause rates on Wednesday and a near 71% likelihood the central bank will keep them unchanged in November, according to CME's FedWatch tool.

In another sign of new market entrants failing to hold on to their strong gains on debut, Instacart lost 5.5% while Arm Holdings was down 4.4%.

Investors are now looking forward to marketing automation company Klaviyo's debut on the New York Stock Exchange, with the stock last indicated to open between $36 and $38.

The Boston-based company had secured a valuation of $9.2 billion in its initial public offering after pricing the shares above their indicated range.

At 11:47 a.m. ET, the Dow Jones Industrial Average was up 190.38 points, or 0.55%, at 34,708.11, the S&P 500 was up 7.87 points, or 0.18%, at 4,451.82, and the Nasdaq Composite was down 24.00 points, or 0.18%, at 13,654.18.

Pinterest added 4.3% as Citigroup upgraded the image-sharing platform to "buy" from "neutral" and as the firm announced a share buyback of up to $1 billion.

Coty added 5.1% after the CoverGirl parent raised its annual like-for-like sales forecast.

Advancing issues outnumbered decliners by a 3.58-to-1 ratio on the NYSE and a 1.59-to-1 ratio on the Nasdaq.

The S&P index recorded 10 new 52-week highs and four new lows, while the Nasdaq recorded 33 new highs and 140 new lows. (Reporting by Ankika Biswas and Shristi Achar A in Bengaluru; Editing by Arun Koyyur and Vinay Dwivedi)