Knight Capital Group Inc. scrambled Thursday to shore itself up and reassure panicked customers after disclosing a stunning $440 million loss from a computer-trading glitch.

Knight officials blamed software installed earlier this week for causing the brokerage firm to enter millions of faulty trades in less than an hour on Wednesday morning. The orders roiled trading in almost 150 stocks and left Knight holding losing positions in many shares at the end of Wednesday's trading session.

As the company's stock slid 63% on Thursday, officials sought out a potential cash injection or buyer, according to people with knowledge of the talks. The firm is working with Sandler O'Neill + Partners LP to help advise on a potential sale. Among those in discussions with Knight is rival trading firm Virtu Financial LLC. J.P. Morgan Chase & Co. was approached to offer funding.

Knight wouldn't comment on the status of the rescue talks. But market participants said the firm is running out of time. In the span of two days, the company's market value has plunged to $253.4 million from $1.01 billion, and its shares continued their nosedive in after-hours trading.

"If they don't get an investor within the next 48 to 72 hours, I think Knight's going to have trouble surviving," said David Simon, chief executive of hedge fund Twin Capital Management LLC.