SEO consultancy staff are constantly watching who’s moving about in the sector, so it was big news to learn that the co-founder of Yahoo, Jerry Yang, was packing his bags.

Yahoo may have lost some ground recently, being surpassed by the likes of Google, but it still remains an essential web and email service for many people. And it is still a massive provider, and what’s more, is valued at some $20 billion.

But, given the debacle over Microsoft, it was perhaps not so surprising that Yang has resigned from all positions within the company.

Yahoo was formed by Yang and David Filo in 1995 and he held the top position of CEO from mid 2007 until early 2009.

Perhaps the appointment of a new CEO, ex PayPal executive Scott Thompson, hastened the decision, but it’s unlikely that Yang’s refusal in 2008 to accept a $47.5 billion bid from software giant’s Microsoft, can have helped endear him to shareholders.

It’s highly unlikely that Yang alone was responsible for spurning Microsoft’s advances, but all senior staff, and advisors, who were involved in the no decision, are unlikely to have much credibility left when it comes to corporate decisions.

To turn down a near $50 billion offer at the onset of the economic downturn, only to find that you’re worth half that nearly four years later, is not a good line for anyone’s CV.

Companies such as Yahoo are not owned by their management, but investment funds who will readily remind the management of how they were robbed of their profits.

The only surprise may well be that Yang survived as long as he did, but, free of the corporate choke, he might have some good ideas to exploit. It’s doubtful we’ve seen the last from him yet.