He actively campaigned against any regulation of derivatives. There is an infamous lunch that he had with Brooksley Born (who was head of the Commodity Futures Trading Commission) in the late 1990s where she attempted to regulate them. The details of the meeting are fuzzy and none of the participants will go on the record to what was said, but the gist is that he said he would fight her tooth and nail. After massive lobbying from Greenspan, as well as Lawrence Summers, congress passed legislation prohibiting her agency from regulating derivatives. She resigned shortly after.