General Electric Co.'s Kristen Michaud is a top client in a business that generates $1 trillion a year for banks—and she's deeply frustrated.

Michaud helps run GE's cash-management system, using 200 banks and 8,000 accounts to move money to remote corners of the world. When sending cash, she doesn't always know how much intermediaries might nibble away in fees or when it will reach suppliers. Payments can pass from bank to bank, arriving in strange amounts with memos erased, leaving recipients confused.

“You might have a supplier calling you up saying they didn't get paid, and then you're spending days working with multiple banking partners to chase down the status,” Michaud says. “It could take multiple days for a bank to respond.”