Nasdaq · May 6, 2010

Prices that vanished for a few minutes (Nasdaq)

-3.44%

single-day change vs previous close

Part of a longer stretch

Two months of Greece and a flash crash

early in it · 2010-04-23 → 2010-07-02, -17.33% over the whole period

What happened that day?

6 May 2010 — the Nasdaq fell 3.44% to close at 2,319.64, after a far deeper intraday collapse that reversed
In the afternoon the major American indices fell apart within minutes and took most of it back within twenty. It is usually called the flash crash
It started with one large institution putting out a huge futures sell order, worked by an algorithm that watched only the share of trading volume, not price or time
Automated programmes reacted to that selling, then reacted to each other, and the buyers disappeared in seconds
Some shares printed at a cent and others at absurdly high prices. The machinery that sets prices briefly stopped working
The Nasdaq holds many names where automated trading is a large share of volume, so it swings harder in such a stretch
The market was already uneasy about Greece. From the late-April high to the 2 July low the index fell 17.33%

Sources

Every figure on this page is recomputed from the original daily closing prices and checked against them at build time. The account of what happened is put together from the public record; where a specific source was consulted it is listed above.