In a story first reported by Kara Swisher at All Things D, Square COO Keith Rabois has stepped down as COO of the mobile payment company. The company gave no information on the reason behind Rabois' abrupt departure, but Swisher cites sources who said disagreements between Rabois and company CEO Jack Dorsey as contributing factors. (See update below including Square's statement.)

Rabois released a statement on his departure. After more than two years at Square, Rabois said only that he wants to be "doing something different every day."

Dorsey's statement on the move was equally vague:

Today I accepted Keith’s resignation from Square. When he joined, we had fewer than 30 employees and under 1000 active merchants. Today, over 3 million individuals and businesses are able to accept credit cards with Square, processing over $10 billion annually. We couldn’t have done it without him and we wish him well in his next opportunity.

For now, Sarah Friar, Square's CFO, will take over as COO.

Update: The Wall Street Journal is reporting Rabois' resignation stems from allegations of sexual harassment from a Square employee. In the report, Square said it had retained an attorney in the matter. Rabois denied the allegations and said he resigned to avoid causing a distraction at the company.

"I'm completely confident that all the facts will come out and I will be vindicated," Rabois said in an interview with the WSJ.

Rabois has responded to the allegations on his personal blog calling the threat a "shakedown" and vowing to defend himself to the full extent of the law.

Square released the following statement:

The first we heard of any of these allegations was when we received the threat of a lawsuit two weeks ago. We took these allegations very seriously and we immediately launched a full investigation to ascertain the facts. While we have not found evidence to support any claims, Keith exercised poor judgment that ultimately undermined his ability to remain an effective leader at Square. We accepted his resignation.

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