Intrexon raised $160 million in its initial public offering to become the 31st biotech company to go public on a U.S. exchange in 2013. The Maryland-based biotech raised the number of shares offered by 20 percent to 10 million and priced at the top of its $14 to $16 a share target range. Shares closed up 54.6 percent in the first day of trading, valuing the company at more than $2 billion.

Intrexon is the second biotech to IPO in August. Marrone Bio Innovations, an agbiotech developing biopesticides and other plant improvement products, raised $57 million in an upsized initial public offering below its target range on August 1.

Intrexon applies proprietary synthetic biology techniques to improve a broad spectrum of products through collaborations with companies in the health, food, energy, and environmental sectors. Founded in 1998 as Genomatix, the company changed its name to Intrexon when Randall Kirk took over as CEO in 2005.

Kirk, a biotech billionaire, made his fortune at companies such as New River Pharmaceuticals and Clinical Data. Intrexon has raised more than $500 million in financing leading up to its IPO. Third Security, an investment firm controlled by Kirk, has led many of the funding rounds, including the latest financing, a $150 million series F round that was completed a few months ago.

This year has been the strongest year for life sciences IPOs since 2000, as the sector continues to outperform the broader markets. As of Thursday, August 8, the 2013 IPO class of companies are up an average of 41.6 percent above their offering prices. A total of 24 companies are trading above their initial offering prices, one is flat, and six are trading below.

While investors are embracing the sector, their attitudes and interests have changed. Less than a year ago, an IPO-worthy biotech had to have a market-ready product or at least one in late-stage development. Now investors’ focus has shifted to companies developing novel approaches to treating cancer and diseases for which no treatment is available, following the shift in priorities of the larger pharmaceutical companies as they seek biotech innovation.

The top-performing companies post-IPO are focused on cutting edge therapies: Bluebird Bio and Prosensa use gene therapy for rare diseases; Stemline Therapeutics targets cancer stem cells, Epizyme focuses on genetically defined cancers; and Onconova has two partnered targeted small molecules to treat cancer in late-stage development for which it has retained rights in many territories including the United States.