Heading into Amazon's IPO twenty years ago, Jeff Bezos had some convincing to do. The company had already increased its price range by two dollars, from $14 to $16 a share.

Bezos wanted to go even higher so the company could raise more cash to invest in customer service and marketing.

John Doerr, the longtime venture capitalist, was the second-biggest shareholder behind Bezos, thanks to an $8 million investment from his firm Kleiner Perkins Caufield & Byers in 1995.

Doerr, who was an Amazon board member until 2010, recalls how Bezos had to push his lead underwriter Frank Quattrone to keep upping the price.

"My most memorable part of the roadshow was the pricing call lasting almost two hours," Doerr said, in an interview with CNBC.com over the weekend. "I remember Jeff asking Quattrone -- `Frank, what would happen if instead of $16 it was $17?'"

Amazon management, its board and the bankers were together on the critical call.

At $16, the deal was already risky. Investors would be placing a $382 million valuation on a two-year-old company that had generated less than $16 million of revenue the prior year and was losing money in a brand new market.

Bezos said to Quattrone, "Can you guarantee for me that it will fail at $17?" Doerr told us.