The company announced in an SEC filing that tomorrow will be de Castro’s last day, and did not provide any information about his successor.

De Castro joined Yahoo in late 2012 after a six year run at Google where his final role was as VP of the company’s global Partner Business Solutions group. Before that he had led Google’s display, mobile and platforms business. Before that he had been with both Dell Corp. and McKinsey & Co.

He was the highest-profile hire for Yahoo CEO Marissa Mayer — also an ex-Googler — and was easily the country’s highest-paid COO. In its SEC filing, Yahoo said that he will receive the severance benefits provided in his employment letter — but did not break it down further or specify any departure-related payments (unclear if this is officially a termination or resignation). He currently holds around 271,000 shares in the company, worth approximately $11.13 million.

Kara Swisher, a tech journalist known for her Yahoo sources, wrote the following after the news broke:

De Castro — who was a polarizing figure at Google, where CEO Marissa Mayer had hired him from — quickly became the same polarizing figure at Yahoo. In recent months, according to numerous sources, he and Mayer had developed a tense relationship that many in meetings with the pair found it hard not to notice.

Besides these interpersonal issues, perhaps most importantly was that De Castro was unable to move the advertising business, which has continued to lag as Mayer’s two-year anniversary nears.

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