Her backers say small entrepreneurs often have to resort to private lending, frequently from investors seeking higher interest rates, because the formal banking system still favors the state-run economy.
"Business people are scared because this is such a common practice in China," said Teng Biao, a Beijing lawyer and activist who has represented several clients fighting the death penalty.
Wu's supporters say she could have paid back the money if her businesses hadn't been shut down so abruptly. Some of her creditors testified on her behalf during the trial.
Since her conviction, the underground banking system in Zhejiang, estimated at $600 million a year, has struggled. Defaults are rampant and many deeply indebted entrepreneurs have fled the country, leaving creditors and their employees in the lurch.
"There are so many of these businessmen who borrowed much more money than Wu Ying, and then ran away. Wu Ying didn't do that. She didn't run. She tried to pay her debts," said Zhang Yanfeng, one of her lawyers.
He described her as "very innocent, almost childlike."
In a letter to her family after she was arrested, Wu expressed regret for what had happened: "If I had a chance to do my life all over again, I would choose to be an ordinary person living an ordinary life."
John Lee and Tommy Yang in The Times' Beijing bureau contributed to this report