For millions of American investors, it's been the best form of whiplash. We're now one year to the day from the stock market's low point — a year in which they more than recouped the stunning losses they saw in the late winter of 2020.

Why it matters: Never before has the market swung so swiftly from extreme pessimism to extreme optimism. Over the past year the S&P 500 has moved from being at a three-year low, to rallying by an astonishing 76% and hitting new all-time highs.

Flashback: The bottom, for the markets, came as the number of COVID-19 cases was still relatively small but rising exponentially, with no end in sight. The only way to prevent millions of deaths was to lock down economies around the world, bringing commerce to a halt and vaporizing trillions of dollars' worth of economic activity.

• The markets were in a tailspin, with the S&P 500 crashing by 34% in the space of just over a month. Only the bravest investors tried to catch that falling knife.
• Since then, the economy has bounced back from its locked-down state, the federal government has approved more than $5 trillion of stimulus — much of which went straight into the market — and the Federal Reserve has promised to do everything in its power to keep money loose and employment rising.

The big picture: Stocks have never risen so much in 12 months. The previous record was a 61% rise ending in June 1983.

• The riskier the asset, the higher the return: Bitcoin has soared by almost 800% over the past year, with Tesla stock not far behind. Safe-haven investments like gold and Treasury bonds have fared much less well.

By the numbers: An investor with a broadly diversified portfolio of stocks and bonds would have seen $1,000 turn into $1,658 over the past year.

• A highly risky bet of $500 each on Bitcoin and Tesla a year ago would be worth $8,221 today.

The bottom line: Americans with investments have done very well over the past year. For the millions of unemployed, however, many of whom have no investments at all, that will come as little comfort.