Have you heard of the Gilder Effect? It's a form of momentum madness that overcomes a stock after it is in the Gilder Technology Report.

Published by techno-visionary, George Gilder, the newsletter influences some investors so much that they jam up its website to get it early each month and then race to buy whatever company Gilder extols. The result is instant run-up - 20, 40, 50 or 60 per cent. The Gilder Technology Report, $295 (#307) per year, is distributed mid-month, online and then by post. Many investors get the newsletter on the Internet at www.gildertech.com, to see if Gilder has added a new stock and then buy it.

George Gilder is a well-known supply-side economist, author and technology futurist who began publishing his newsletter in 1996.

The newsletter notes that he and his staff "may hold positions in some or all stocks listed". Investors should however tread cautiously when considering stocks that have been mobbed - or Gilderised.