Twitter shares tumble 10% as lock-up period expires (Cnbc)

Twitter dropped sharply Tuesday as nearly 500 million shares of the social media giant from company insiders became eligible to be sold.

The stock fell more than 10 percent Tuesday to a fresh all-time low. Click here to see how the stock is trading.

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Last week, the social media giant said its net loss grew by more than $100 million in the first quarter, though the company's operating earnings and sales topped Street expectations. Monthly active users hit 255 million, with mobile MAUs making up 78 percent of the total.Twitter's co-founders, Jack Dorsey and Evan Williams, and Chief Executive Dick Costolo said in April that they did not plan to sell their shares after the restrictions were lifted.

Venture capital firm Benchmark, which holds a roughly 6 percent stake, has also said it would not sell its stake.

But other major shareholders could see an opportunity to cash out, given that none of Twitter's insiders sold their shares during the IPO.

Many tech companies, including Twitter, have a share lock-up clause to prevent holders from flooding the market as soon as the company goes public.

Twitter has already allowed one batch of shares to be sold in February, but that lockup governed only about 10 million shares, most of which were held by non-executive employees.