NEW YORK (TheStreet) -- Shares of Nektar Therapeutics (NKTR - Get Report) were falling on heavy trading volume mid-Wednesday afternoon after the biopharmaceutical company said it would sell 13 million shares of common stock for $13.50 apiece.

The offering has been priced below the stock's Tuesday closing price of $14.08.

Nektar is giving underwriters 30 days to buy up to 1.95 million additional shares. JPMorgan is the lead book-running manager in the offering.

The company will use the proceeds from the sale to fund general corporate operations including research and development efforts as well as working capital.

Nektar first announced the public offering on Monday.

More than 8.18 million shares of the San Francisco-based company have traded hands so far today vs. the 30-day average volume of 1.44 million shares.

Separately, TheStreet Ratings objectively rated this stock according to its "risk-adjusted" total return prospect over a 12-month investment horizon. Not based on the news in any given day, the rating may differ from Jim Cramer's view or that of this articles's author.

TheStreet Ratings rated this stock as a "sell" with a ratings score of D-.

Among the areas we feel are negative, one of the most important has been the company's poor growth in earnings per share.

You can view the full analysis from the report here: NKTR