(Reuters) - U.S. stock index futures edged lower on Friday as megacap tech and chip stocks lost ground, with investors awaiting manufacturing and services sectors surveys for more clues on the health of the world's largest economy.

The S&P 500 crossed the 5,500 point milestone during Thursday's session, however, both the benchmark index and the Nasdaq closed lower as shares of megacap stocks pulled back.

Nvidia dropped 1.5% in premarket trading on Friday, after losses in the previous session saw its market valuation fall back below that of Microsoft.

Other chipmakers Broadcom, Super Micro Computer and Qualcomm were down between 0.8% and 1.2%, while Microsoft's shares fell 0.2% and Apple was down 0.3%.

Later in the day, numbers for the manufacturing and services sectors are expected to fall slightly, but remain above the 50 level that shows activity is still expanding.

Wall Street has rallied in recent months, primarily driven by the likes of Nvidia and a handful of other stocks linked to artificial intelligence.

Investors are also assessing a string of weakening economic data, and commentary from the U.S. Federal Reserve that interest rates could remain higher for longer if there is no consistent improvement in inflation data.

Minneapolis Fed President Neel Kashkari said on Thursday it would take a year or two to get inflation back to 2%, as wage growth might still be too high.

Still, all three major Wall Street indexes are on track to close the week higher, as is the small-cap focused Russell 2000.

Money markets are pricing in a 64% chance of a 25-basis point interest rate cut at the Fed's meeting in September, and still expect about two rate cuts this year, according to LSEG's FedWatch data.

Friday's session will also mark the expiry of quarterly derivatives contracts tied to stocks, index options and futures, also known as "triple witching".

At 5:49 a.m. ET, Dow e-minis were down 26 points, or 0.07%, S&P 500 e-minis were down 8.25 points, or 0.15%, and Nasdaq 100 e-minis were down 24.75 points, or 0.12%.

Drugmaker Gilead's shares jumped 6.4%, extending gains from the previous session as a late-stage study showed its long-acting injectable drug was more effective in preventing HIV infection in women compared to its existing daily pill Truvada.

Sarepta Therapeutics soared 34% after the U.S. Food and Drug Administration allowed the expanded use of the company's gene therapy for patients with Duchenne muscular dystrophy aged four and older.