Wall Street Missed Warning Signs When Backing $1 Billion Fintech

Every week during the years leading up to its sudden collapse in December, Stenn Technologies sent an email to some of the world’s biggest finance firms.

The emails contained pages of data from a trade-finance deal that London-based Stenn had arranged that grew to almost $1 billion in size, according to documents reviewed by Bloomberg and people familiar with the matter. Citigroup Inc., BNP Paribas SA, Natixis and HSBC Holdings Plc were among the biggest investors while Barclays Plc, M&G Plc and Goldman Sachs Group Inc.’s asset-management unit had also backed the transaction.

The arrangement was ...