STORY: GameStop shares sank almost a fifth on Thursday (June 8).

The videogame retailer's worst session in two years comes after the surprise exit of its fifth CEO in five years.

Former Amazon.com executive Matt Furlong's departure has raised concerns about the company.

GameStop was due to lose half of its gains for this year and about $1.3 billion in market value, going by premarket share movements.

GameStop shares saw a massive rally during the health crisis, driven by traders coming together on Reddit.

It was among the most prominent of the so-called "meme stocks".

That led several brokerages to say the stock price had decoupled from its fundamentals.

Company shares have dropped almost 80% in value since their $120 peak during the meme-stock frenzy.

Top shareholder Ryan Cohen had pledged to make GameStop the Amazon of videogame stores, but the company has struggled to deliver.

GameStop reported its fourth straight fall in quarterly revenue on Wednesday (June 7) and a bigger-than-expected loss.