Shares of Progyny (PGNY) , the New York benefits-management concern specializing in fertility, soared as much as 23% in their first day of trading.

Progyny priced its initial public offering on Thursday: 10 million common shares at $13. Progyny offered 6.7 million shares and selling stockholders offered 3.3 million shares.

In addition, the holders granted the underwriters an option on as many as 1.5 million more shares.

The offering is expected to close Tuesday. JP Morgan, Goldman Sachs and Bank of America Securities are the lead underwriters.

Progyny stock finished the day at $15.94, up 20%. It traded as high at $16.

This article is commentary by an independent contributor. At the time of publication, the author held  positions in Goldman Sachs and J.P. Morgan.