It's like a scene out of the latest Wall Street-bashing Hollywood blockbuster. One of the most respected financial institutions in the United States, and the third-largest bank in the world, just admitted to fleecing its customers on such a massive scale that at least 5,300 employees were involved in the scam which went on unabated for at least five years.

Wells Fargo has just been fined a record $185 million by federal and California state regulators for widespread fraud, in which bank employees opened extra accounts for customers without their permission and signed them up for credit cards they didn't want. To keep customers from catching on, bank employees routinely created false email addresses for customers where notices about these unwanted accounts were sent. As a result, customers were hit with late fees on credit cards they didn't know they had, and overdraft fees because money in a legitimate account had been transferred to an unauthorized one. In all, Wells Fargo employees opened more than 2 million unauthorized bank and credit card accounts. The bank says it has fired 5,300 employees over their involvement in this widespread fraud.

It's a shocking story, but there are a few lessons smart leaders can draw from it:

1. Sales incentives can do more harm than good.

Regulators say the widespread scam was a direct result of Wells Fargo's emphasis on cross-selling and the fact that it created lucrative incentives for employees who could get existing customers to open additional accounts. In the win-at-all-costs atmosphere that pervades much of the financial industry, the banks' leaders should have known where that compensation structure might lead. It's depressing to note that compensation schemes like these are common, especially in the financial world.

2. Just because a company has a golden reputation doesn't mean you can trust it.

If reputation was a reliable indicator of trustworthiness, it would be hard to do better than Wells Fargo. The 164-year-old bank was named the most valuable bank brand in the world by The Banker in 2014. Even the beloved and legendary investor Warren Buffett has invested heavily in it--Berkshire Hathaway owns almost 10 percent of Wells Fargo.

3. Always check your bank statement. Twice.

The fraud has been going on since at least 2011 when the Consumer Financial Protection Bureau was formed. Yet no one did much of anything about it until the Los Angeles City Attorney's Office sued Wells Fargo over this issue in May 2015. In the meantime, the bank collected millions of dollars in late fees, overdraft fees, annual fees, and other fees to which it was not entitled, and which it will now have to repay.

With millions of customers affected, you have to wonder why it took so long for the malfeasance to be noticed. The only possible explanation is that most customers weren't looking closely at their bank statements--even though they're readily available online.

If that describes you, it may be that you've been assuming your bank can be trusted, and if there's a discrepancy, it's likelier to be your error than theirs. If so, then it's time to stop trusting--and start keeping a better watch over your money.