The search engine has not given a reason for his departure but he appears to have been fired by Mayer.
In a staff email Mayer said that during "my own reflection", she made "the difficult decision" that COO, Henrique de Castro, should leave the company.
It is a little worrying that anyone should make decisions while looking at their own reflection.
At the time of de Castro's hiring, Mayer was building a management team to try to revive flagging sales and traffic, and cited de Castro's internet advertising expertise as a key asset.
But he was known for his tough talk and a strong personality, and a bulky compensation package totalling $58 million when he was hired. How is he going to spend it all before he croaks?
The fact that Mayer managed to lure an executive from Google was applauded as a sign that the new CEO had re-inspired confidence in the company.
However de Castro failed to do much other than collect his salary. Yahoo's revenue growth has remained moribund. Revenue has declined between five percent and seven percent year-over-year in each of the first three quarters of 2013.
Ironically he will get severance benefits including equity awards, according to the filing.
De Castro could not immediately be reached for comment as he was trying to pack his rubber plant.