Obama clinches; Dow Jones Average drops 72 points in 9 minutes.--

At 1:23pm ET, an AP story was released, reporting that Hillary Clinton would concede tonight because Barack Obama has clinched the nomination. [Although I don't have the original timestamp for the more definitive AP story that their delegate tally showed that Obama had won, the earliest timestamp I've found so far is Breitbart's at 1:26pm ET. That may well be the more relevant trigger.]

At 1:23pm, the Dow Jones Industrial Average, which was at 12,493 and had been marking time for hours, immediately started dropping [at 1:25, it was at 12,483]. In 9 minutes (1:32) [after 1:23], it had dropped 72 points to 12,421. After another 23 minutes (1:55), it had fallen another 53 points, resulting in a 125 point drop in 32 minutes. It then stabilized, indeed rebounding a bit.

This is not a particularly large drop (it's less than 1%), but the probable trigger was much clearer this time than for market responses to other primary wins and losses.

UPDATE (3:25pm): In the comments below, several people seem to be attributing the sudden drop to Bernanke's speech. While such a delayed reaction is possible, the juxtaposition I noted seems more likely. Here are two stories from earlier today on the market's response to Bernanke's speech, which seemed to be positive:

Wall Street moves higher after Bernanke speech

3 hrs ago - Wall Street rose tentatively Tuesday as investors were torn between troubling fears about inflation and more reassuring signs that the U.S. economic downturn is nearing an end. Federal Reserve Chairman Ben Bernanke reiterated expectations that the economy will rebound during the second half due to interest rate cuts, Fed loans to banks and tax rebates. But, the Fed chief, in a speech via satellite to a conference in Barcelona, Spain, said the economy faces headwinds with rising prices for food and energy - a signal that interest rates will remain on hold.

Wall Street opens higher after Bernanke speech

5 hrs ago - Wall Street opened modestly higher Tuesday after Federal Reserve Chairman Ben Bernanke reiterated expectations the economy will improve later this year. After the central bank's recent interest rate cuts, loans to banks and tax rebates, the second half of the year should bring "somewhat better economic conditions," Bernanke said in a speech in Spain. The economy faces headwinds, however, and the inflation picture remains uncertain, he said, indicating that the Fed still intends to keep interest rates on hold.