By Anna Isaac

U.S. stock futures drifted Wednesday following the S&P 500 edging up to record highs on three consecutive trading days.

Futures tied to the S&P 500 were largely flat, suggesting that the benchmark index may waver after the New York opening bell. Overseas, the pan-continental Stoxx Europe 600 edged up 0.2%. In Asia, major stock gauges ended the day on a mixed note.

Volatility in American stocks has been muted through much of August, with many investors and traders taking summer vacations in the U.S. and Europe. The Cboe Volatility Index, a closely watched gauge of turbulence in U.S. stocks, has in recent days been at its lowest since before the coronavirus pandemic capsized markets.

In the bond market, the yield on the benchmark 10-year U.S. Treasury note edged up to 0.703%, from 0.680% Tuesday. It briefly hit 0.719%, its highest in intraday trading in almost two weeks, according to Tradeweb. The Treasury yield is ticking up for a third day in a sign that investors' risk appetite is improving, reflecting rising optimism about prospects for the pandemic-battered U.S. economy.

In recent weeks, investors have grown confident that the Federal Reserve and other major central banks will continue to bolster the economy by holding short-term interest rates low and buying government bonds and other forms of debt. That's pushing yields from sovereign debt, considered among the safest assets to own, below expected inflation levels and prompted investors to look for higher returns in riskier assets.

"There's still trillions of dollars on the sidelines in money-market funds. It needs to be deployed and the only real home for it is equities, " said Edward Park, deputy chief investment officer at Brooks Macdonald. "If there's a recession next year, or bond yields increase meaningfully from where there are right now, that changes the story. But that's unlikely, particularly with expectations of the Fed changing policy."

Markets are anticipating fresh cues on the health of the U.S. economy and potential changes to monetary policy on Thursday, when Fed Chairman Jerome Powell is expected to signal shifts to the central bank's approach to managing inflation at the annual Jackson Hole Economic Policy Symposium.

Investors are also watching the progress of hurricane Laura as it gathers strength and churns toward Texas and Louisiana. The hurricane is expected to produce a life-threatening storm surge, extreme winds, and flash flooding over eastern Texas and Louisiana, the National Hurricane Centre said at 2 a.m. ET.

Brent crude, the international oil benchmark, edged up 0.1% to $46.36 a barrel, while U.S. crude prices were largely flat. Stockpiles of fuel are presently high due to the pandemic's impact on demand, potentially minimizing the disruption on energy prices from the storms. Gasoline futures, which on Monday surged to their highest level since early March, fell 0.8% Wednesday.

"It's too early to tell if there's going to be major economic damage yet, " said Mr. Park. "At the moment, it seems to be playing out over concerns over the oil price, rather than a border impact on the equity market."

New orders for long-lasting manufactured goods, due 8:30 a.m. ET, are likely to reflect broader economic trends in July by notching another month of growth, but at a slower pace. Underlying figures are likely to show business investment remains subdued at a time of broad economic uncertainty.

Write to Anna Isaac at anna.isaac@wsj.com