'Very busy' Ballmer steps down from Microsoft board

Impending start of the basketball season partly behind the move

Ex-Microsoft boss Steve Ballmer has stepped down from the company's board of directors after becoming "very busy" in his retirement.

Ballmer still holds more Microsoft shares than anyone else - other than index funds - and said he expects that to continue for the foreseeable future.

His resignation was effective immediately after he sent a letter to his successor Satya Nadella last night. He insisted he could still be counted on to "keep ideas and inputs flowing".

Back in May, Ballmer outbid Oracle boss and fellow multi-billionaire Larry Ellison to buy US basketball team the LA Clippers for a reported $2bn (£1.2bn). Ballmer said the upcoming basketball season was a factor in his resignation.

"[With the] multitude of new commitments I am taking on now, I think it would be impractical for me to continue to serve on the board, and it is best for me to move off," he said in a public note to Nadella.

"In the six months since leaving, I have become very busy. I see a combination of the Clippers, civic contribution, teaching and study taking a lot of time."

He added that he thought Nadella had made a "bold and exciting start" in his role, and said the company will still be a big part of his life.

"I bleed Microsoft - I have for 34 years and I always will," he said.

In Nadella's reply, he said Ballmer's insights and leadership will be "greatly missed", but added that he supports his decision.