Altimmune Inc. is planning to raise about $13 million via a units offering to two investors.

The Gaithersburg, Md.-based immunotherapy focused biotechnology company agreed to sell 4,361,370 units, which consisted of common units and pre-funded units.

The company is offering 1.5 million common units, with each common unit consists of one common stock and 0.70 of a warrant to buy a single common share for $3.21. Each common unit is being sold at $3.21 apiece.

Altimmune is also offering 2,861,370 pre-funded units. Each pre-funded unit consists of a pre-funded warrant to buy one common stock at 1 cent per share and 0.70 of a warrant to buy one common share for $3.21. Each pre-funded unit will be offered at $3.20 per unit.

The pre-funded units will be offered to buyers whose purchase of common units in the offering will lead to them owning more than 4.99% of the company's outstanding common stock.

Altimmune expects to raise about $13.0 million, excluding any funds from the exercise of the warrants, and other expenses.

The company plans to use the net proceeds for working capital and other general corporate purposes.

Roth Capital Partners LLC is acting as the placement agent for the offering, which is expected to close March 12, subject to customary closing conditions.