single day, and it created a "circuit-breaker" mechanism to halt all trading temporarily any time the DJIA dropped 250 points. Those emergency mechanisms were later substantially adjusted to reflect the large rise in the DJIA level. In late 1998, one change required program-trading curbs whenever the DJIA rose or fell 2 percent in one day from a certain average recent close; in late 1999, this formula meant that program trading would be halted by a market change of about 210 points. The new rules set also a higher threshold for halting all trading; during the fourth quarter of 1999, that would occur if there was at least a 1,050-point DJIA drop. Those reforms may have helped restore confidence, but a strong performance by the economy may have been even more important. Unlike its performance in 1929, the Federal Reserve made it clear it would ease credit conditions to ensure that investors could meet their margin calls and could continue operating. Partly as a result, the crash of 1987 was quickly erased as the market surged to new highs. In the early 1990s, the Dow Jones Industrial Average topped 3,000, and in 1999 it topped the 11,000 mark. What's more, the volume of trading rose enormously. While trading of 5 million shares was considered a hectic day on the New York Stock Exchange in the 1960s, more than a thousand-million shares were exchanged on some days in 1997 and 1998. On the Nasdaq, such share days were routine by 1998.