Theranos is going out with barely a whisper. Once heralded as a revolutionary new way to conduct a blood test to detect myriad diseases, all with a single finger prick, the company is making preparations to close its operations, according to a letter sent to shareholders.

“We are now out of time,” David Taylor, the company’s chief executive and general counsel, informed investors in an email first reported on Tuesday by The Wall Street Journal, whose in-depth investigation unraveled the company’s claims. Mr. Taylor declined to comment further, saying the letter spoke for itself.

Theranos’s efforts are now focused on avoiding bankruptcy.

It’s in default under a credit agreement reached last year with Fortress Investment Group, Mr. Taylor told shareholders. The company is negotiating a settlement with Fortress, which would then own the company’s intellectual property and allow Theranos to distribute its remaining cash — some $5 million — to unsecured creditors .

“Because the company’s cash is not nearly sufficient to pay all of the creditors in full, there will be no distribution to shareholders” under the plan, Mr. Taylor said in the letter.