The Federal Reserve will start easing its vast support for financial markets this month, marking a highly anticipated policy change as central bank leaders grapple with major price increases in some parts of the economy but plenty of room to grow in the labor market.

The Fed’s announcement, made after its two-day policy meeting concluded Wednesday, comes as the economy continues to shift more than 18 months after the pandemic first hammered U.S. labor and financial markets. The S&P 500 and other stock indexes closed at record highs Wednesday amid fresh optimism about the economy’s direction, but other concerns persist, including inflation, supply chain issues and a disconnect between many unfilled jobs and unemployed workers.

The coronavirus’s delta variant appears to be finally easing, leading to a pickup in hiring. But inflation concerns that the Fed has long labeled as “transitory,” or temporary, haven’t yet receded. Fed leaders Wednesday pointed to the persistence of “sizable price increases in some sectors,” and Chair Jerome H. Powell said at a news conference that inflation and related supply chain issues “will persist well into next year.”

The Fed had provided extraordinary support to the economy since the height of the pandemic to help money flow through the economy, limit bankruptcies and try to stopgap the wave of layoffs that washed across the United States last year.

For months, the Fed had set the stage to start winding down this sprawling bond-buying program — which includes $120 billion a month in asset purchases — in November. Those purchases have helped stimulate the economy and made borrowing easier by holding down long-term rates, and the expectation was that the purchases will be fully drawn down before the Fed raises interest rates. On Wednesday, the Fed announced it would be cutting purchases by $15 billion each month.

That decision reflected optimism within the Fed that the economy is on the right track. But tremendous uncertainty still hangs over the economy, especially when it comes to how long prices will keep rising faster than wages, a phenomenon many Washington policy makers did not expect to last so long. Following the Fed’s policy meeting, officials released a statement saying that the mismatch of supply and demand, plus the reopening of the economy, has contributed to high prices.

Powell said he didn’t expect that inflation will have a permanent imprint on the economy, and added that the central bank will use its tools “to make sure that doesn’t become a permanent feature of life,” especially for households most sensitive to higher prices for groceries, rent, gas and more.

Now that the Fed has started its long-awaited “taper,” the markets are hungry for signals about when the central bank will raise interest rates for the first time since the pandemic. But Powell emphasized patience, arguing that the Fed would wait to cool the economy down until as many people as possible have gotten back into jobs. He said that it is “certainly within the realm of possibility” that the economy could reach full employment by the second half of next year. But reflecting on the recent surge of the delta variant, which had a harsher toll on the economy than the Fed expected, Powell reiterated that “we have to be humble about what we know about this economy.”

“There’s still ground to cover to get to maximum employment, and we don’t want to stop that when there’s good reason to think — although it’s been delayed — that the economy will reopen if we do get past significant outbreaks of covid,” Powell said.

Wednesday’s policy announcement was no surprise: Powell and other Fed leaders have sent strong signals for months that the taper would probably begin in November, if the economy progressed as expected. The Fed noted that it could adjust the pacing of the taper depending on “changes in the economic outlook.” Yet Powell declined to offer more details on what would cause the Fed to speed up or slow down the process.

The policy decision comes at a precarious time for the economy — and for the central bank, which is charged with keeping prices stable and fostering full employment. The Fed is also limited in how it can fix holes in the economy, with Powell saying that “our tools cannot ease supply constraints.”

Inflation has climbed higher and lasted longer than policymakers within the Fed and Biden administration initially expected. Officials point to persistent supply chain issues that were exacerbated by the delta variant. They say prices won’t settle back down closer to the Fed’s 2 percent annual target until those backlogs are able to clear. (In September, the Fed’s preferred gauge for inflation clocked in at 4.4 percent.)

Meanwhile, the labor market has lagged, with weak job growth in August and September showing how vulnerable the economy still is to covid-19. This week, Treasury Secretary Janet L. Yellen argued that child-care issues and the ongoing pandemic are the main factors holding back the labor market, and Powell echoed that message Wednesday. Still, there are encouraging signs that the economy is poised for an uptick in hiring.

The Fed’s main tool to combat inflation is interest rates, which it can raise or lower depending on what is unfolding in the economy. But Fed leaders are hesitant to hike rates — and cool the economy — if that means undercutting job growth.

Only time will tell if Fed leaders get the timing right. The Fed’s most recent crop of economic projections showed officials moving up expectations for a rate hike in 2022.

But already, inflation has become a flash point in Washington and the rest of the country. Republicans argue that the Biden administration’s vast spending is fueling rising costs and that the Fed will be behind the curve once it decides to raise rates.

“Today’s decision by the Fed to begin tapering is welcome but long overdue,” Sen. Patrick J. Toomey (Pa.), the top Republican on the Senate Banking Committee, said in a statement. “As I warned this spring, the Fed’s overly accommodative monetary policy risked leaving [the Fed] behind the curve if inflation persisted. And as any American family can tell you, inflation is real, and it’s worse than expected.”

Meanwhile, other issues loom over the central bank. Powell’s term as chair expires in February, and the White House has not made a decision on whether he will be reappointed or whom it will nominate for a slate of other openings on the Fed board. Powell on Wednesday declined to answer any questions about the renomination process.

“I’ve been meeting with economic advisers on what the best choices are. We’ve got a lot of good choices, but I’m not going to speculate now,” President Biden said during a Tuesday news conference in Glasgow, Scotland.

Since the Fed’s last policy meeting in September, two Fed regional bank presidents also have exited their posts over their stock-trading behavior. That spurred an independent inspector general probe into whether those activities violated ethics rules and the law. The Fed also announced a major tightening of its internal rules overseeing the personal financial activities of top officials. On Wednesday, Powell said he had briefed officials in the Biden administration and on Capitol Hill about the Fed’s ethics issues.