The company priced 8 million shares at $5 per share. The stock was down 43 cents, or 8.6 percent, to $4.57 in late Friday trading.
The Redwood City, Calif., company said it expected $40 million in gross proceeds from its IPO. The underwriters of the offering have the option to buy another 1.2 million shares. Earlier this month, AcelRx said it expected to sell 5.8 million shares at $12 to $14 per share, which would have brought proceeds of more than $60 million.
AcelRx is running clinical trials for a device designed to treat severe pain, and pain that is not being helped by analgesic drugs. It does not have any products on the market.