(For a Reuters live blog on U.S., UK and European stock markets, click LIVE/ or type LIVE/ in a news window.) * IBM tumbles after missing quarterly revenue estimates * AT&T rises as it adds more wireless subscribers * Futures off: Dow 0.17%, S&P 0.17%, Nasdaq 0.20% (Adds comments, details, updates prices throughout) Oct 21 (Reuters) - U.S. stock indexes were set to open lower on Thursday as IBM and Tesla fell after their quarterly results, with investors awaiting more reports to see the impact of supply chain disruption and labor shortages on companies. Some market players pointed to fading enthusiasm after the Dow Jones Industrials Average hit an intraday record high in the previous session and the benchmark index came close to its early September record. “Stocks are climbing to new highs and anytime the market is trading at or near its all-time high, it is not unusual to see a little bit of more intraday volatility...and it should not concern investors,” said Tom Mantione, managing director, UBS Private Wealth Management in Stamford, Connecticut. Tesla Inc fell 1.4% in premarket trading as it said on Wednesday its upcoming factories and supply-chain hurdles would put pressure on its margins after it beat Wall Street expectations for third-quarter revenue. Other mega-cap stocks including Facebook Inc, Apple Inc and Amazon.com Inc fell between 0.2% and 0.3% on Thursday. IBM tumbled 5.1% after it missed market estimates for quarterly revenue as its managed infrastructure business suffered from a decline in orders. Investors are keeping a close eye on growth outlook from companies facing rising costs, labor shortages and supply chain disruptions, with analysts expecting profit of S&P 500 companies to rise 33% from a year earlier, according to Refinitiv data. “Large parts of the S&P are not going to be impacted - software, healthcare, real estate, utilities, energy, materials, financials would not see any of that as an issue,” Mantione said. Data showed the number of Americans filing new claims for unemployment benefits dropped to a 19-month low last week, pointing to a tightening labor market, though a shortage of workers could keep the pace of hiring moderate in October. At 8:42 a.m. ET, Dow e-minis were down 59 points, or 0.17%, S&P 500 e-minis were down 7.75 points, or 0.17%, and Nasdaq 100 e-minis were down 30.75 points, or 0.2%. AT&T Inc rose 1.2% after the telecom operator’s quarterly revenue and monthly phone bill paying subscriber additions beat market expectations. American Airlines rose 0.8% after posting a smaller-than-expected quarterly loss, while Southwest Airlines Co edged 0.3% lower even as it posted a smaller third-quarter loss. HP Inc gained 4.4% as brokerages raised their price targets on the stock after the PC and printer maker forecast upbeat fiscal 2022 adjusted profit and raised its annual dividend. (Reporting by Shreyashi Sanyal and Devik Jain in Bengaluru; Editing by Arun Koyyur)