As measured by the speed of pleasantly surprised reaction in financial markets, in reaction to a very minor change in a statement issued by the Federal Reserve' Open Market Committee (FOMC) after increasing interest rates as expected today:
I'd say the spike in the Dow Jones Industrial index (DJI), Standard & Poor 500 index (GSPC), and Nasdaq index (IXIC) all happened at about the exact time the following news was reported:
2:15PM: As expected, the FOMC has raised the fed funds rate by 25 basis points to 4.25% and maintains that some further measured policy firming is likely; however, the Fed did drop the reference with regard to "policy accomodation." NYSE Adv/Dec 1489/1752, Nasdaq Adv/Dec 1232/1726
Source: Yahoo! Finance Market Update on December 13, 2005