"It does not take much analysis to say that all Internet pure-play stocks, including Amazon.com, are extremely vulnerable — they can be up 20 percent a day and down 20 percent a day," Jeff Bezos told Reuters.

"In my opinion these are not appropriate investments for small investors, or maybe all but the smallest fraction of their portfolio, and they are certainly not investments for any investor who is a short-term investor," he said.

Amazon has ridden a wave of interest in Internet stocks to around $117 a share from a 1998 low of below $9, but Amazon founder Bezos said he didn't waste time worrying about the price.

"In Internet business, customer value is created. So over the long term the Internet is going to work out. Businesses are going to thrive on the Internet, customers are going to thrive, people are going to create important and lasting companies.

"As to what the share prices should be at any given stage — that is a very complex question. If you look at Amazon.com, the people at Amazon.com, we do not spend very much time every day thinking about the share price because for us every second thinking about the share price is a second wasted."

Bezos, who was in Davos to attend the World Economic Forum's annual meeting, a global business summit, said the bookseller's goal was building a lasting company.

"That is a full-time job and it is the full-time job of the Wall street analysts and investors to try and figure out how much these companies are worth. I do not envy them their job — it's a hard one."

He declined to comment on the question when Amazon.com might start turning a profit. It made a loss of 14 cents a share in the latest quarter, worse than the 8 cents a share loss a year earlier, but this was still better than Wall Street expected, so its shares went up again.

Bezos played down prospects that the millennium bug, or year 2000 (Y2K) problem, would lay waste to the computer world at the turn of the year, but said the bug may still sneak up on people.

"The problem is that even if companies do a good job of eliminating the Y2K dependencies from their own systems, you do not know if all of your vendors have eliminated the Y2K dependencies from their systems," he said.

"It is impossible for any company to assure that there are no Y2K problems. But ... my guess is that because there has been so much hype maybe nothing will happen."