Shares of American Airlines Group (AAL -1.05%) jumped 15% on Monday after Pfizer reported a significant milestone toward the development of a COVID-19 vaccine. On Tuesday, American announced plans to sell shares into that rally, seeking to raise about $500 million in additional liquidity.

American and other airlines have been hit hard by the pandemic, and with travel volumes not expected to return to pre-pandemic levels for years, the industry has been scrambling to raise cash to weather the crisis.

An American Airlines jet airborne over the clouds.

Image source: American Airlines.

American, on Tuesday morning, said that it intends to sell 38.5 million shares of its common stock, with an underwriter allotment to buy an additional 5.78 million shares, with the proceeds used for general corporate purposes and to enhance liquidity. At the company's $13.20 closing price on Monday, the offering would raise $508.2 million before the underwriter's option.

The airline bled through about $44 million in cash per day in the third quarter, and expects to burn between $25 million and $30 million per day in the current quarter. The company ended the quarter with $13.6 billion in available liquidity, but given the uncertainty about the pandemic and how long it will take for passengers to return carriers are trying to raise as much cash as possible.

The offering is a positive development for American holders, as the additional cash makes it more likely the airline can survive the crisis. However, it is a reminder that survival comes at a cost to shareholders in terms of dilution, and the airlines who do survive will have bruised balance sheets for years due to the added debt taken on in 2020.