Unister Holdings, owner of online travel agencies fluege.de, AB-in-den-Urlaub.de, and Reisen.de, is hoping to be sold whole or in part.*
*UPDATE 1800 ET:
Tnooz's message to the company's press office accidentally fell into a spam folder. Since publication, a spokesperson for Unister Travel has told us:

"The company said in public in summer 2014 that it has been seeking strategic partnerships. This process has never had a firm deadline."
The effort to find strategic partners followed a reorganization in 2014, aided by the consultancy Ernst & Young, that intended to make Unister Travel a standalone entity whose profitability was clear.
Unister Travel is the largest homegrown online travel agency (OTA) in Germany, as measured by the volume of arranged travels, according to trade magazine FVW.
The company is said to have sold about Euro 2 billion of travel products last year. That compares to Expedia Inc brands selling Euro 1.1 billion and Holidaycheck selling Euro 765 million, as estimated by FVW last summer.
Last year the holding company reported Euro 690 million in revenue, the bulk of which came from the travel division, according to Reuters.
Unister's solvency now depends on loans of up to Euro 50 million from an insurance company, HanseMerkur, with repayment reportedly past due since October, according to a report earlier this month by financial publisher Handelsblatt.
UPDATE 1800 ET: A company spokesperson tells Tnooz:

"Unister Travel itself has with no doubt a much higher profit than parent company Unister Holding. We deny your speculations about solvency problems."
An executive A source who was not authorized to speak to reporters confirmed a few details. CORRECTION 1 Dec 0800 ET: I misunderstood the rank of my source. The person is not an executive, but only a department head. I apologize for my mistake.--Sean
Unister Travel is an operating company owned by Unister Holding and operating profitably, said the source.
For at least 10 months, Unister has sought "strategic partners" for this travel division, said the source.

UPDATE 1 Dec 800 ET: As noted above, Unister Holding's press office says that, since summer 2014, it has been seeking strategic partnerships.
Tnooz's source had no comment on that Handelsblatt report except to dismiss as false Handelsblatt's claims that German e-commerce giant CTS Eventim was a serious bidder on the business.
Some payments to travel agents have "faced complications" in recent months, the source claimed, though the blame was placed on the liquidity problems at the larger financial entity that owns the travel division.
UPDATE 1 Dec 800 ET:

The company's spokesperson again has said that speculations about solvency problems are wrong and that the alleged "complications" in payments to travel agents are false. A few travel agents thought that commissions under 100 Euro went out monthly, but that was not the policy. Last Friday, there was a follow-up report from German-language trade publication Touristik Aktuell that said the issue had been resolved through standard processes.
Reuters recently reported that Unister has been negotiating a deal worth Euro 700 million to 1 billion, with investment bank Jefferies representing the company.
Possibly complicating any potential sale may be the fact that public prosecutors in Leipzig have charged the company's founder Thomas Wagner and four other managers with tax fraud and the violations of other laws.
UPDATE 1800 ET:
A spokesperson for Unister Travel has since contacted Tnooz to say:

"Even almost three years after starting public investigations, there is no valid prosecution against the managers of Unister. We believe in their innocence."
Unlike in the consolidated US, a dozen viable OTA brands still battle it out in Germany.
In a comment on the larger European OTA scene, Phocuswright has noted:

"Just five years ago, the top four European OTAs represented 45% of the marketplace. In 2014, that figure swelled to 70%."
UPDATE 1 Dec 0800 ET:
As a look ahead, the company points readers to its German-language press release of 12 November, which says that it has moved its package tour OTA Ab-In-den-Urlaub.de into a new Ab-In-the holiday operating company, a wholly owned subsidiary of the Unister Travel travel operating company. Thomas Wagner is managing director of the new independent company under the Unister group umbrella.