NanoString Technologies Inc. priced a public offering of common shares at $23 each.

The Seattle-based company is selling 2.5 million common shares under the offer, while private equity fund Clarus Lifesciences II LP, a NanoString stockholder, will sell 2 million shares. NanoString will not receive proceeds from the sale by Cambridge, Mass.-based Clarus.

NanoString also granted underwriters a 30-day option to buy up to an additional 675,000 common shares at the same price.

The company plans to use proceeds for working capital and general corporate purposes. The offer is expected to close on or about March 22.

J.P. Morgan, UBS Investment Bank and Cowen are acting as joint book-running managers for the offering, while Baird is acting as lead manager.

NanoString Technologies is a provider of life science tools for translational research and molecular diagnostic products.