Anitbiotics developer Cempra Pharmaceuticals (Nasdaq: CEMP) has completed a $25 million private placement of additional shares.

The shares were sold on Oct. 24 at a price of $6.50

Cempra announced the stock sale agreement with “new and existing institutional and accredited investors.”

A major backer of Cempra is Durham-based Intersouth Partners.

Cempra shares closed at $6.65, down 31 cents or 4 percent, on Friday.

Shares traded at $7.81 when the placement was announced on Oct. 18 and closed at $6.90 the next day. Shares fell to as low as $6.14 on Oct. 23.

“Proceeds from the private placement are expected to be used for general corporate and working capital purposes, including the funding of clinical trials,” Cempra said in announcing the deal.