Stocks fell more than 4% on Thursday, extending the market’s worst week since the financial crisis in 2008 following a spike in coronavirus cases around the world.

The big picture: All three indices are in correction, down over 10% from recent record-highs, amid a global market rout. It's the S&P 500's quickest decline into correction territory in the index's history, per Deutsche Bank.

February saw one of the most effective ways of destroying wealth, thanks to the gyrations in the stock market. More broadly, institutions and individuals around the world have been getting better and better at vacuuming up money and keeping it from doing useful things in the economy as a whole.

Driving the news: Stocks went up this month and then they went down. The rise in stocks coincided with sustained buying pressure — a lot of money entered the market as it was going up. Then the fall came suddenly, not so much as a result of selling pressure, more as a result of the market reacting to coronavirus news by simply marking down the valuation of most stocks.

The bond market set a significant milestone on Thursday, with bond yields — as measured by the yield on the benchmark 10-year Treasury note — dropping below 1.3% for the first time in history.

By the numbers: The yield was above 3% as recently as November 2018.

Karma says that if something bad happens to you now, you probably did something to deserve it. So what did Credit Karma do to deserve being bought by Intuit?

Driving the news: Credit Karma is the most successful of the apps built around giving people their credit score for free. It had about $1 billion in revenue in 2019, and served some 37 million monthly active users. Now it's being bought by Intuit for $7.1 billion.

When you give something away, people are likely to consume far too much of it. That's true of food, it's true of drink, and it's true of options trades.

Why it matters: The best thing that an investor can do is nothing. People who actively trade the market are effectively trying to time it — to buy low and sell high. Voluminous literature has shown that it just doesn't work, and that doing nothing is superior to doing something a significant majority of the time.

The stock market selloff has drawn the most attention this week, but moves in the U.S. government debt market will likely have much more important impacts on the economy.

The state of play: Mass bond buying has taken place since the beginning of the year and picked up steam as headlines about the spread of novel coronavirus have grown more worrisome.

Economists are rethinking projections about the broader economic consequences of the coronavirus outbreak after a surge of diagnoses and deaths outside Asia and an announcement from a top CDC official that Americans should be prepared for the virus to spread here.

What's happening: The coronavirus quickly went from an also-ran concern to the most talked-about issue at the National Association for Business Economics policy conference in Washington, D.C.

The Treasury held an incredibly weak auction of 2-year government debt Tuesday that saw primary dealers, who are essentially on clean-up duty, take home their highest share of the auction since December 2018.

What it means: Even though yields on the 2-year note have fallen by nearly 40 basis points this year, traders are convinced that there is "certainly more room for yields to fall," Ben Jeffery, rates analyst at BMO Capital Markets, tells Axios.

When President Trump launched the U.S. into a trade war in 2018, many fund managers argued that small-cap stocks were poised to outperform because their business would be immune to tariffs and uncertainty.

What's happening: They did well over the course of that year but after Tuesday's 3.5% decline, the Russell 2000 index, which tracks many of the nation's small public companies, has fallen to near its closing level from February 2018.

The stock market fell another 3% on Tuesday, following Monday’s sell-off. Bond yields touched record lows.

The big picture: Stocks continued to fall as the CDC said it expects the coronavirus to spread in the U.S. The Dow and S&P are more than 7% below the record highs seen earlier this month.