Yahoo wiped out the entire value of the mystery company it bought for $23 million last year

In May 2015, Yahoo disclosed in a regulatory filing that it spent $23 million on an unnamed company based outside of the US.

The mystery acquisition seemed odd, given the scant details provided in the filing and the fact that Yahoo was at the time slowing down a buying spree which amounted to dozens of startups in 3 years.

Yahoo still hasn't disclosed the name of the company or the rationale behind that particular transaction. But it did reveal one important footnote about the company in its latest filing on Tuesday: the entire goodwill value of the company has been written off.

"The entire goodwill amount which was recorded in the EMEA segment was subsequently impaired during the fourth quarter of 2015 as a result of the impairment testing performed by the Company on its reporting units as of October 31, 2015," Yahoo wrote in the filing.

Yahoo said that the goodwill portion of the deal, which represents the amount paid for the company beyond what is valued on the balance sheet, was $22 million - meaning the entire value that Yahoo overpaid for the mystery company has been wiped out over the past year.

The write off amount is small relative to Yahoo's overall business, which generated over $1 billion in revenue last quarter alone. It also doesn't affect Yahoo's actual cash holdings since the deal was completed last year. Yahoo stressed that the transaction didn't have a "material impact" on the company's business in the filing.

Yahoo was not immediately available for comment. But the write off leaves another black mark on Yahoo CEO Marissa Mayer's failed strategy to find growth through acquisitions.

M&A freeze

Despite spending an estimated nearly $3 billion on buying startups, Yahoo's revenue growth has been stagnant over the past few years. It also disclosed in its fourth quarter earnings that it would write off more than $1 billion from acquisitions occurred after 2012, including $230 million on Tumblr.

Investors have been unhappy with this strategy for some time. SpringOwl Asset Management's Eric Jackson, one of the most vocal critics of Yahoo, wrote in his famous 99-page presentation that the acquisitions have "resulted in zero additional value."

And with activist investors breathing down her neck to cut back, Mayer hinted in the fourth quarter earnings call that Yahoo would put the brakes on buying companies.

At least Mayer seems to be sticking to her promise: Yahoo did not make any acquisitions during the three months ended March 31, 2016, according to the filing on Tuesday.