The assault on Microsoft had started a year or two earlier, but the rulings on Microsoft were coming to a head later that spring. The CONTEMPT of Joel Klein and Janet Reno for Microsoft and virtually ALL PRIVATE INDUSTRY was just stunning and, I believe, chilling to investors and business leaders.
The refusal to allow Worldcom and Sprint combine (yes, it would have been a horrible combination, in retrospect, but that wasn't the reason the Justice Department didn't allow the combination) was another terrible signal that discouraged investors.
All of these things, along with the internet/technology bubble, led to the wipe-out of $7 trillion of investor "wealth" (or perceived wealth). Sorry to disagree with people who don't buy into a "wealth-effect" on our economy: you don't have $7 trillion evaporate and not have a significant impact on the economy or growth.
Most of the carnage took place before President Bush came into office in late January, 2001.