May 17 (Reuters) - Retail darling GameStop slumped 20% in premarket trading on Friday, after the struggling videogame retailer announced a mixed-shelf offering, taking advantage of share gains as meme stocks frenzy took hold this week.

The company also expects its first-quarter net sales to drop from a year ago, as customers transition to buying video games and collectibles online, while the retailer largely relies on brick and mortar stores.

Under a mixed-shelf offering, a company can raise capital by selling different types of securities in one or more separate offerings. The size of GameStop's offering was not disclosed.

"Companies have also learned to take advantage of the market disruption with quicker secondary offerings," said Rick Meckler, partner at Cherry Lane Investments.

The Grapevine, Texas-based firm caught retail traders' attention this week following a series of posts from Keith Gill's X account "Roaring Kitty", whose bullish calls on GameStop were a reason for the 2021 meme-stock frenzy.

Secondary offerings "can blunt price rises by meeting demand with additional new shares being supplied", Meckler said.

GameStop said its first-quarter net sales were expected to be in the range of $872 million to $892 million, down from $1.237 billion a year ago.

Net loss in the quarter ended May 4 is expected to be between $27 million and $37 million, narrower than the $50.5 million a year ago, as GameStop benefits from cost cuts.

The stock has erased half of its gains since the two-day rally in the beginning of the week when it rose to as much as $64.83.

(Reporting by Akash Sriram and Medha Singh in Bengaluru; Editing by Shilpi Majumdar)