Yahoo COO Henrique de Castro is reportedly departing the internet major on 16 January after serving the internet major for more than a year.

The ex-Google employee was hired by Yahoo CEO Marissa Mayer by luring him with a four-year $58m compensation in October 2012and was responsible for strategic and operational management of the company’s global sales, media, business development and operations.

Though the reasons for his exit is a secret, the latest move is a blow to the firm’s efforts to stimulate declining sales and internet traffic, with rising competition from rivals including Google and Facebook.

However, technology website Re/code cited Mayer’s memo which suggested that she reportedly fired De Castro as part of an internal restructure.

Mayer wrote: "During my own reflection, I made the difficult decision that our COO, Henrique de Castro, should leave the company."

"I appreciate Henrique’s contributions and wish him the best in his future endeavours," she added.

The departure of Yahoo’s second most senior executive would be an expensive loss for Mayer as he has to be paid a multi-million-dollar severance package.

Yahoo said in a filing with the US Security Exchange Commission that Castro will be leaving the Company effective 16 January 2014.

"Mr. de Castro will receive the severance benefits provided for in his Employment Offer Letter, dated October 15, 2012, Severance Agreement, dated February 28, 2013, and equity award agreements," the filing said.