"According to Kreia's predictions before her death on Malachor V, the Exchange grew in power, until the Hutt's ceased tolerating the Exchange, causing it to slowly feed upon itself and decline. The sudden decline could likely be due to G0-T0's abscence.
By the time of the Clone Wars, the Exchange seemed to have faded away, though many independent crime lords still held sway over the galaxy."
-Taken from wookieepedia.