Shares of youth apparel retailer rue21 Inc rose in their debut on the Nasdaq, opening 26.3 percent over Thursday's initial public offering and putting the company on pace for one of the biggest first-day performances of an IPO this year.

Rue21, which operates 500 stores in the United States geared at youths, raised a total of about $128.5 million in the IPO, which priced at $19, above expectations.

In midmorning trade on the Nasdaq, shares were being quoted at $23.33, up 22.8 percent.

The Warrendale, Pennsylvania-based retailer itself is selling 1.65 million shares in the offering, while stockholders such BNP Paribas North America are selling 6.77 million shares.

Funds advised by private equity firm Apax Partners, which is the largest stockholder, are not selling any shares in the IPO. Their stake in rue21 will fall to 57.9 percent from 62.2 percent.

Rue21's same-store sales, or sales at stores open for at least a year, rose 4.1 percent in the six months ended Aug. 1, 2009, while overall sales rose 33.3 percent to $233.1 million, with net income of $8.3 million.

 (Reporting by Clare Baldwin and Phil Wahba, editing by Matthew Lewis)