It’s basically official at this point: The Federal Reserve will soon wind down its pandemic-era stimulus measures, a process Wall Street nerds call “tapering.” But what, exactly, does that mean? And why does it put investors on edge?

The short answer: Money is essentially free now, thanks to the Fed’s double-barrel shotgun approach to economic stimulus — interest rates near zero and a massive investment in bonds that keeps yields near rock-bottom. If the Fed eases off the stimulus pedal, borrowing could grow more expensive, making businesses pay more, which means less profit which means Wall Street is sad.

For a more in-depth answer, read on!

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The conversation about tapering will only accelerate this fall, and while it might sound somewhat academic, the results of the Fed’s decision could have a huge impact on everyday people, especially those looking to buy a home or run a business.

The coronavirus crash

To understand how we got here, we have to flash back to March of 2020, when Covid-19 landed like a bomb on US shores. Businesses shut down, at least 20 million people lost their jobs in a single month, and Wall Street was in full-on panic mode. In just under a month, the S&P 500, the broadest measure of Wall Street, lost more than 30% of its value. If you peeked at your retirement account during that time, it was a grim sight.

As Congress bickered over what to do, the Federal Reserve essentially threw itself on top of the Covid bomb to prevent a total financial and economic collapse. It did that by buying government-backed debt — lots of it.

Without getting too in the weeds about the Fed’s balance sheet, the thing to understand here is that a big part of the central bank’s job is to ensure stability, and it does that by controlling the amount of money sloshing around. By buying up debt, the Fed was essentially turning on a money spigot.

And it has been keeping that up for the past year and a half, to the tune of about $120 billion a month in Treasury bonds and mortgage-backed securities.

With that supply of easy money, investors came back from the brink in the spring of 2020. By April, the stock market began to rebound, even as the broader economy plunged deeper into crisis and the public health crisis worsened. That disconnect between Wall Street and Main Street persists in part because the Fed has kept interest rates near zero and assured investors it would continue its easy-money policy for as long as needed to get the economy back on track.

Pumping the brakes

Those debt purchases were emergency measures implemented to stave off calamity, and were always expected to be rolled back once it was clear the economy had enough momentum to recover from the short-lived but severe pandemic recession of 2020.

The good news is the economic recovery is chugging along as more people get vaccinated, return to work, and in many ways resume their pre-pandemic lives. That means it’s time for the Fed to wind down, or taper, its debt purchases.

It’s a delicate process, and Fed Chairman Jerome Powell has been cautious, and at times cryptic, about how and when the taper will begin. Slamming the brakes would trigger an investor panic, but not slowing down would fuel inflation.

Avoiding a ‘taper tantrum’

The Fed is clearly trying to avoid a repeat of the so-called taper tantrum of 2013.

At that time, the Fed triggered a panic by merely mentioning its plans to eventually scale back its Treasury bond purchases — a policy known as quantitative easing, or QE, which is just a nerdy way to say pumping cash into the economy. The Fed began its QE policy in response to the 2008 recession, and investors got accustomed to the easy money.

The mention of a future taper caught bond investors off guard, and they began selling en masse. Bond prices plummeted, which meant yields (which move inversely to prices) shot up.

High yields on bonds lead to higher mortgage rates. They make it more expensive for businesses to grow by taking on debt. That’s very bad news for an economy in recovery, and exactly the scenario the Fed is trying to avoid.

When will the Fed pull back?

The Fed hasn’t provided a date for unwinding its debt purchases, but analysts broadly expected it to begin this fall. Goldman Sachs predicts the Fed will begin the process in November, at a rate of about $15 billion each month.

On Friday, in his highly anticipated speech at the virtual Jackson Hole Symposium, Powell was optimistic about tapering before the end of this year, but he tempered that optimism with some words of caution: The Delta variant remains a looming threat to the US economy.

By now, a fall taper should come as no surprise to anyone on Wall Street. The stock market seemed to take Friday’s taper talk in stride: US stocks were in the green, with all three major stock indexes adding to modest gains following Powell’s speech. The yield on the 10-year Treasury bond edged lower, down 0.02% at 1.32%.

— CNN Business’ Anneken Tappe contributed reporting.

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