Shares in World Poker Tour parent WPT Enterprises continued to tumble Wednesday after an unsolicited $700 million bid for the company from poker champion Doyle Brunson expired Tuesday without any follow-up.

A private-equity team led by Mr. Brunson made the offer last week, saying the company, which produces the “World Poker Tour” television series, had until 5:30 p.m. (ET) Tuesday to accept or reject the bid.

The company sought additional information about the offer, which some people familiar with the matter described as vague, but was told by Mr. Brunson that no additional information was forthcoming. That led to market speculation that Mr. Brunson’s offer was not in earnest.

In any event, news of the deal’s expiration led WPTE shares to fall more than 5 percent Wednesday to around $20.82 a share at midday, after falling 12.5 percent Monday and another 5 percent on Tuesday.

News of the offer sent the company’s stock price surging 50 percent to $29 last Friday.