SoftBank Group Corp. has used its stake in online retailer Alibaba Group Holding Ltd. as collateral for an $8 billion loan from a group of banks in what is one of the biggest deals of its kind, according to people familiar with the matter.

Morgan Stanley, Citigroup Inc., Goldman Sachs Group Inc., Bank of America Corp. and JPMorgan Chase & Co. were among at least 10 banks that helped to make the so-called margin loan, which is guaranteed only by SoftBank's Alibaba holding, said the sources, who requested anonymity as the details are not public. The deal won't be reflected in the Tokyo-based company's debt, which may help shield it from a ratings downgrade, and could help its plans to sell shares in a domestic subsidiary, the people said.

The participation of the world's biggest banks in the trade reflects their continued appetite for complex share-based trades linked to their most-prized clients, even after banks lost more than $1 billion combined on a margin loan linked to Steinhoff International Holdings NV.