Dollar General and Rue21 both surged in their trading debuts Friday after the retailers priced at opposite ends of the spectrum.

Dollar General (NasdaqGS:DG - News), which owns a chain of over 8,500 discount stores around the U.S., priced at $21, the low end of its expected range. The sale of 34.1 million shares made for total proceeds of $716 million.

Some analysts weren't surprised by the low pricing. Morningstar analyst Zoe Tan had called the IPO "high interest" due to Dollar General's striking financial turnaround since KKR took it private in 2007. But she also estimated a fair value at $18.

Investors seemed to disagree. During Friday's trading they drove up the price by 8% to 22.73.

Rue21's offering was smaller, but highly lucrative. It priced 6.77 million shares at $19 apiece, above the expected $16-$18 range. During trading hours it stormed up 28% to 24.30.

Rue21 is a teen-oriented apparel retailer with about 500 stores in 43 states, mostly in the South. Like Dollar General, it focuses on value pricing. Stores are largely in strip malls in low-rent areas, often sharing lots with Wal-Mart (NYSE:WMT - News).

Both retailers seem to be profiting from the recessionary trade-down effect. Each recorded double-digit same-store sales growth in its most recent reported period, while many chains were negative.

The two firms' strong debuts signaled a possible comeback for retail IPOs, which had been absent from December 2007, when Titan Machinery (NasdaqGS:TITN - News) debuted, until Oct. 28, when Vitamin Shoppe (NYSE:VSI - News) came out. Vitamin Shoppe is up 17% from its $17 initial price.

What the two IPOs had in common with other new issues this year, however, was a lot of insider selling. A third of Dollar General's shares and more than 75% of Rue21's came from selling shareholders. According to a Nov. 5 report by R.W. Baird, 30.2% of 2009 IPO shares have been sold by insiders vs. just 15% in 2007 and 4.5% in 2000.

IPO activity has picked up in recent weeks as companies take advantage of the general market rally to raise capital and provide an exit strategy for owners.