Zynga Inc. and Michael Kors Holdings Ltd. are leading the biggest week for U.S. initial public offerings in nine months, betting their surging sales will attract investors.

Zynga, the largest maker of games on Facebook, luxury clothing designer Kors Holdings and nine other companies are seeking as much as $3.8 billion in IPOs this week, data compiled by Bloomberg show. That's the most since the five days starting March 7, when HCA Holdings Inc. raised $4.4 billion.

Zynga's management team, led by Chief Executive Officer Mark Pincus, has been telling investors in roadshow presentations that the company is working on its biggest ever pipeline of online games. Zynga's sales more than doubled in the nine months through Sept. 30, while Kors Holdings' revenue jumped more than 60 percent in its first half, even as consumer confidence sank to the lowest level since the recession.