Twitter CEO Dick Costolo. Flickr/Fortune Twitter CEO Dick Costolo made nearly $5.1 million after dumping 140,352 shares of company stock early this month, according to a Securities and Exchange Commission filing.

This isn't the first recent sale. In November and December of 2014, he sold more than 500,000 shares, including all the stocks owned by his family trusts.

That means he's now sold more than $25 million worth of stock since November.

The latest filing shows that Costolo sold his shares over two days, on Jan. 2 and Jan. 5. He also appears to have exercised some options over the same period, and still owns a little more than 810,000 Twitter shares. If you add that to all of his unexercised stock options, Costolo’s total share amounts to roughly 9 million shares.

The sale comes at a precarious time for Costolo. Several investors have called for his resignation, with one major shareholder telling us, “He shouldn’t be running the company anymore.”

Twitter stock closed down 3.8% at $37.28 on Wednesday, after rising almost 7% the previous day thanks to speculation about the company, including a comment from former interim Yahoo CEO Ross Levinsohn that Twitter should buy Yahoo's core media business.

Twitter sent us this statement regarding Costolo's stock sale:

"Dick has sold shares under a plan filed in the summer and his total sales represent less than 10% of his total equity in Twitter."

NOW WATCH: Psychiatrist Reveals 5 Ways To Have Healthy And Meaningful Relationships