On May 8 evening, U.S. stock index futures traded flat as a series of Federal Reserve officials warned that interest rates might remain elevated for some time, dampening recent Wall Street rebound momentum. Federal Reserve officials are scheduled to deliver more speeches on Thursday and Friday, particularly as recent data indicate a slowdown in U.S. economic growth, further grabbing market attention.

Disappointing quarterly reports also weighed on market sentiment, with shares of chipmaker Arm (NASDAQ: ARM) and home rental platform Airbnb (NASDAQ: ABNB) declining in after-hours trading.

As of 7:16 p.m. (23:16 Greenwich Mean Time), S&P 500 index futures edged down 0.1%, to 5209.75 points, Nasdaq 100 index futures fell 0.1%, to 18163.75 points, while Dow Jones index futures held steady at 39196.0 points.

Following a string of warnings from Federal Reserve members that the central bank is more likely to keep rates unchanged this year due to robust inflation, Wall Street's recent rebound stalled on May 8th. They believe persistent inflation concerns are the primary factor in maintaining rate stability, despite recent data showing some slowing in the labor market, which is also one of the factors the Federal Reserve needs to consider.

The Fed's stance has led to an increase in currency and bond yields, putting pressure on the stock market. The S&P 500 index closed basically flat on Wednesday, at 5187.67 points, while the Nasdaq Composite index fell by about 0.2%, to 16302.76 points.

The Dow Jones Industrial Average rose by 0.4%, to 39056.39 points, benefiting from the rise in shares of U.S. pharmaceutical company Amgen (NASDAQ: AMGN), as investors maintain an optimistic outlook on the company's weight loss injection drug.

In the coming days, more Federal Reserve officials will speak, including Mary Daly, President of the Federal Reserve Bank of San Francisco, on May 9th, and Charles Evans, President of the Federal Reserve Bank of Chicago, on Friday.

UK chip design company Arm fell nearly 10% in afternoon trading due to disappointing annual revenue expectations. Although quarterly profits in March exceeded expectations, concerns about the lack of outlook for the company's recent AI-driven valuation plunge have arisen as to whether it is reasonable.

Arm's disclosure led to losses in chip manufacturers NVIDIA Corporation (NASDAQ: NVDA) and Advanced Micro Devices, Inc. (NASDAQ: AMD) in after-hours trading. AMD's quarterly profit in March roughly met expectations, while NVIDIA plans to release its quarterly report next week.

Airbnb fell 7% due to poor annual performance outlook, while Bumble (NASDAQ: BMBL) rose due to strong expected growth in performance.

Robinhood Markets, Inc. (NASDAQ: HOOD) rose by about 4% after reporting strong quarterly performance and user growth.