The Dow lost 85 points. The S&P 500 gained 7 and the Nasdaq rose 104 points.
Hugh Johnson of Hugh Johnson Advisors says the Fed will have to tread lightly between inflation worries and a healing labor market.
"I think really what matters is that they're very careful about how they word what they're going to do. And when I say very careful, they don't want to send a message to the financial markets as far as our policy is going to start to, let's call it, lean toward restraint, that seems to imply that not only are we going to start to reduce the securities that they're buying in the financial markets, but also that they're going to raise interest rates. So they want to be very careful to word it very carefully."
Tesla shares rose slightly after CEO Elon Musk hinted in a tweet that his electric car company might resume accepting bitcoin for payment sometime in the future.
Bitcoin, by the way, jumped back above $40,000 after Musk showed it some love.
It was a tough day for electric truck maker Lordstown Motors after its CEO and CFO resigned days after warning it may not have enough cash to stay in business over the next year. The stock slumped nearly 19 percent.
In health news, Novavax said its vaccine is more than 90 percent effective after a large, late-stage clinical trial. It plans to file for emergency authorization in the U.S. sometime during the third quarter. The stock traded modestly lower.
Meanwhile, public health officials in the UK say the Pfizer/BioNTech vaccine is 96 percent effective against the new Delta variant on the rise there, while the AstraZeneca shot is 92 percent effective. AstraZeneca shares ended flat. Pfizer and BioNtech were down for the day.