Updates with market open prices

By Nikhil Sharma and Pranav Kashyap

Aug 5 (Reuters) - Wall Street's main indexes gave up opening gains on Tuesday after data showed U.S. services activity stalled, while investors continued to assess the latest batch of corporate earnings.

At 10:07 a.m. ET, the Dow Jones Industrial Average .DJI fell 63.46 points, or 0.14%, to 44,110.18, and the S&P 500 .SPX lost 1.86 points, or 0.03%, to 6,328.08. The Nasdaq Composite .IXIC gained 37.45 points, or 0.18%, to 21,091.04.

U.S. services sector growth unexpectedly stalled in July, as new orders barely budged and hiring slipped further - even as input costs soared at their fastest pace in nearly three years - highlighting how uncertainty around the Trump administration's tariff policy continues to weigh on businesses.

Wall Street had roared back to life on Monday by posting its best session since May 27 and recouping last week's losses when disappointing July jobs data and sharp downward revisions to prior months fueled expectations of a Fed rate cut in September.

As per CME Group's FedWatch tool, odds of a September cut stands at 90%, up sharply from 63.3% just a week ago - and market watchers are eyeing at least two quarter-point cuts by year-end.

Earnings from major names on Tuesday include Advanced Micro Devices AMD.O, Snap SNAP.K and Rivian RIVN.O.

Pfizer PFE.N gained 3.6% in after raising its annual profit forecast, while Palantir Technologies PLTR.O rose 8.6% as it boosted itsannual revenue forecast.

Meanwhile, President Donald Trump's decision to fire the head of the Bureau of Labor Statistics, responsible for past jobs data, stoked investors' fears about the integrity of economic data.

Trump on a CNBC interview said he would "shortly" announce his pick for an open seat on the Federal Reserve's board of governors and possibly his nominee for Fed chair as well.

"You can announce who the next chair is, but I don't think that Chair Powell will be going anywhere until the end of his term. I also don't think that whoever is announced as the new Fed chair will really be impactful," said Art Hogan, chief market strategist at B Riley Wealth.

Investors also weighed the impact of U.S. tariffs on global economies and corporate earnings. Trump signaled that the U.S. could soon slap a "small tariff" on pharmaceutical imports, with the potential for steeper rates down the line. He also hinted at progress toward a trade deal with China, suggesting a possible meeting with President Xi Jinping by this year's end if talks succeed.

Beyond last week's jobs data jolt, Wall Street has stayed buoyant, fueled by blockbuster earnings from the "Magnificent 7" tech giants, with Nvidia's NVDA.O results on deck in three weeks. Reflecting the market's upbeat mood, HSBC just boosted its S&P 500 year-end target by more than 800 points to 6,400, citing AI excitement and easing U.S. policy uncertainty.

Caterpillar CAT.N slipped 0.3% after reporting a lower second-quarter profit, hurt by sluggish demand for construction equipment and higher costs tied to U.S. tariffs.

KFC parent Yum Brands YUM.N fell 2.8% after missing estimates for second-quarter comparable sales and profit.

Advancing issues outnumbered decliners by a 1.29-to-1 ratio on the NYSE and by a 1.07-to-1 ratio on the Nasdaq.

The S&P 500 posted 31 new 52-week highs and four new lows, while the Nasdaq Composite recorded 54 new highs and 40 new lows.

(Reporting by Nikhil Sharma and Pranav Kashyap in Bengaluru; Additional reporting by Twesha Dikshit; Editing by Maju Samuel)

((Nikhil.Sharma@thomsonreuters.com; pranav.kashyap@tr.com))