The enormous losses reflect the deep fears gripping markets about how the world economy will fare amid a deepening economic slowdown in China.

The Dow, S&P 500 and Nasdaq have all tumbled into correction territory, their first such 10% decline from a recent high since 2011.

The S&P 500 -- the best barometer for the biggest U.S. companies -- has lost trillions of market value, according to S&P Dow Jones Indices.

To put those losses into perspective, that's roughly equal to the combined market value of these corporate titans put together: Apple (AAPL, Tech30), Google (GOOGL, Tech30), Berkshire Hathaway (BRKA), ExxonMobil (XOM), Facebook (FB, Tech30), Walmart (WMT) and 21st Century Fox (FOXA).

Here's another way to look at it: It's like erasing almost the entire value of the British version of the S&P 500. Known as the S&P BMI U.K. Index, it is worth just $2.8 trillion.