April 25 (Reuters) - Shares of blank-check firm Cantor Equity Partners CEP.O surged 29% on Friday, extending a scorching rally from their previous session, as retail investors hoping to capitalize on the growing interest in bitcoin flocked to the stock.

The stock had the ninth-highest message volumes in the last 24 hours on Stocktwits.com, a social media platform focused on retail investors. The company's market value has nearly tripled since it announced a $3.6 billion crypto venture on Wednesday.

The venture, called Twenty One Capital, aims to be a publicly traded bitcoin-holding company. Such companies allow investors to gain exposure to the cryptocurrency without directly owning it.

Once a niche idea, bitcoin-holding companies have gained traction after the exponential growth of Michael Saylor's Strategy MSTR.O. Since pivoting to bitcoin in 2020, Strategy's shares have jumped more than 27-fold.

"Strategy became a proxy bitcoin play, and many traders are on the lookout for the next one," said Brett Reeves, head of Go Network and European Sales at crypto infrastructure firm BitGo.

"The significant investment from SoftBank and Tether adds to the credibility and potential appeal for investors."

Twenty One will be launched in partnership with stablecoin issuer Tether, Japanese investment giant SoftBank 9984.T and crypto exchange Bitfinex.

In its presentation, Twenty One emphasized that it is a more "pure play" bitcoin company and could be a "potentially superior vehicle" when compared to Strategy, which still has a small business software unit despite its bitcoin focus.

Cantor Equity is backed by Cantor Fitzgerald, an investment banking and brokerage firm chaired by Brandon Lutnick, the son of U.S. Secretary of Commerce Howard Lutnick.

(Reporting by Niket Nishant in Bengaluru; Editing by Shilpi Majumdar)

((Niket.Nishant@thomsonreuters.com))