Shake Shack is up 20%

Shake Shack is soaring.

Shares of the burger chain gained more than 20% in afternoon trading on Wednesday to as high as $63.50.

There was no immediate news on the company, which is scheduled to report second-quarter results on August 10.

But before then, the lockup period, during which insiders cannot sell their shares, expires today. That would free up additional outstanding shares for trade.

Shake Shack shares have rallied 32% from the IPO, and the company is now worth about $2.3 billion.

Here's a chart showing the jump in shares on Wednesday:

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