If people wanted additional stock to fill their positions, they could buy the shares in the open market. That made the Google Dutch auction IPO more like conventional IPOs that use the traditional underwriting process.

The only thing different was individual and institutional buyers got equal treatment –- partially filled orders, which forced them into the aftermarket to buy more shares and complete their positions.

The Google IPO opened with a $15-a-share premium, and traded about 22.4 million shares on its opening day. That volume exceeded the offering’s size of 19.6 million shares.

It would look as if unfilled orders were left on the table, to bid the Google IPO higher once it started trading.