March 24 (Reuters) - An affiliate of private equity firm Apollo Global Management Inc is looking to raise $400 million for a blank-check company through a U.S. initial public offering $(IPO.UK)$, a regulatory filing showed on Wednesday.

Spartan Acquisition Corp IV, a special purpose acquisition company (SPAC), said it planned to sell 40 million units, composed of shares and warrants, priced at $10 per unit on the Nasdaq Capital Market.

SPACs are shell companies that raise money with the purpose of merging with an operating company to take it public.

Once confined to obscurity in the capital markets, SPACs have surged in popularity over the past year as they allow companies to sidestep a traditional IPO and the hassles and scrutiny associated with it.

In less than three months since the start of 2021, SPACs have already raised more capital through IPOs than the entire haul of 2020, which was itself a record year, according to data from SPAC Research.

Apollo, a global alternative asset management firm, has raised hundreds of millions of dollars through multiple blank-check companies to date, with some of its SPACs already landing deals.

Spartan Energy Acquisition Corp, an Apollo-backed SPAC, took electric vehicle maker Fisker Inc public last year for $2.9 billion.

Goldman Sachs, Citigroup, Credit Suisse, J.P. Morgan, Barclays and RBC Capital Markets are the book-running managers for the latest offering.

(Reporting by Sohini Podder in Bengaluru; Editing by Aditya Soni)

((sohini.podder@thomsonreuters.com;))