Arm Ltd. has filled out the roster of underwriters for its initial public offering, with 28 banks in all on the deal, people familiar with the matter said.

In addition to four lead banks — Barclays Plc, Goldman Sachs Group Inc., JPMorgan Chase & Co. and Mizuho Financial Group — the offering will have 10 second-tier underwriters, including Bank of America Corp. Citigroup Inc., Deutsche Bank AG and Jefferies Financial Group Inc., the people said, asking not to be identified because the information was private.

A third-tier consists of a diverse group of 14 securities firms, such as Daiwa Securities Group Inc., HSBC Holdings Plc, Intesa Sanpaolo SpA and Societe Generale SA, they said.

A representative for Arm, which is majority owned by SoftBank Group Corp., declined to comment.

The Cambridge, UK-based chipmaker has been seeking to raise $8 billion to $10 billion in September in what would be the year’s biggest IPO, Bloomberg News has reported. The company is aiming to be valued in the listing at $60 billion to $70 billion.