Typos and math errors might not seem like such a big deal — unless, of course, you’re a billion-dollar company.

Some of these corporations lost millions thanks to embarrassing human errors that didn’t get caught in time. Make sure to learn from these mistakes: With 9.3 million Americans still looking for work, now is not the time to put your job security at risk.

From major financial institutions to popular fast-food joints, here are 10 businesses that made enormous blunders.

10. Citibank overpays by $892 million

This mortifying financial error was recently incurred by New York-based Citibank.

Three employees accidentally processed an interest payment that transferred a whopping $900 million to Revlon lenders, reported Bloomberg in 2020. They were supposed to send $8 million.

The bank has managed to recover $390 million so far.

In May, a judge denied Citi’s request to keep the remaining $510 million frozen while it tries to persuade a court it deserves to get the money back.

9. Samsung Securities spills shares worth $105 billion

An employee at Samsung Securities, a South Korean financial branch under the larger Samsung umbrella, doled out almost three billion shares into employee accounts in 2018 — more than 30 times the number of Samsung’s existing shares.

The employee was supposed to pay out 1,000 won ($0.88 U.S.) per share in dividends, but confused won for shares, explains The Wall Street Journal.

While the company blocked employees from selling their newly acquired shares 37 minutes later, the damage had already been done. Several staff members sold close to $187 million worth of shares within the half hour.

If that sounds like a pretty appealing bonus, you should know a popular investing app gives out a free stock to new users. If you're lucky, the stock could be from a major company like Visa, Microsoft or Facebook.

8. Alitalia prices tickets to Cyprus for $33 each

In 2006, an employee at Italian airline Alitalia forgot to input the two extra zeros when pricing business-class tickets from Toronto to Cyprus.

A business-class ticket from Toronto to Cyprus would have cost $2,558, according to the Wall Street Journal. Due to the exchange rate on that day and the clerical error, hundreds of buyers managed to snag fares for just $33.

The airline did the right thing and chose to honor the heavily discounted price for the 509 people who bought airline tickets before the error was detected, reports CBC News.

7. Whopper of a discount at Burger King costs $8.2 million

Everyone loves a good two-for-one burger deal. But a discount gone wrong cost this franchisee millions.

In 2019, Burger King franchisee Carrols Restaurant Group offered “two Whopper Jr. sandwiches for $4, two Whoppers for $5 and two Double Whoppers for $6,” according to the Syracuse Post-Standard. Customers were supposed to be charged full-value on fries and drinks on their orders but were charged discounted prices on those as well.

The bungle cost restaurants about $1.50 on each sale — adding up to $8.2 million overall.

6. Zappos sister site loses $1.6 million in fire sale

Discount clothing site 6pm once capped every item in the store at $49.95, according to a 2010 article by Fast Company.

The retailer carries a number of luxury brands that “can reach into the thousands of dollars,” so plenty of bargain hunters managed to snag some ridiculously good deals.

6pm ended up honoring the sales, which occurred within a six-hour time frame, costing parent company Zappos (owned by Amazon) more than $1.6 million.

5. Uber owes drivers $45 million due to accounting mistake

Gig work can be incredibly lucrative, but one of the biggest names in the space, Uber, is often in the news for its strained relationship with workers.

In 2017, the ride-sharer admitted it made an embarrassing accounting error by overcalculating its commission cut.

The error went all the way back to 2014 and was estimated to cost the company up to $45 million in refunds, including interest.

The ride-sharing company told Quartz that it would refund the affected “tens of thousands” of drivers around $900 each.

4. Mizuho Securities trader tries to sell 610,000 shares at 1 yen apiece

In 2005, a trader from Japanese firm Mizuho Securities was trying to sell a single share of J-Com Co. for 610,000 yen ($5,513 U.S.).

A typing error caused him to sell 610,000 shares at 1 yen apiece instead — 41 times the number of existing shares.

Fox News says another trader tried to cancel the order, but since the Tokyo Stock Exchange (TSE) doesn’t cancel orders, the error ended up costing Mizuho Securities $335 million.

TSE president Takuo Tsurushima resigned shortly after the debacle, admitting that the exchange was partly to blame, and Mizuho Securities attempted to sue for over 40 billion yen.

3. Spreadsheet error costs JPMorgan $3.1 billion

You might recall the “London Whale” incident in 2012, when notorious trader Bruno Iksil — whose other monikers include the White Whale and even Voldemort — conducted a series of credit default swaps that cost JPMorgan Chase $6.2 billion.

What you might not know, however, is that half the loss was incurred by a simple Excel spreadsheet error.

Bloomberg reports that the Excel model, which relied heavily on copy and pasting of information, accidentally “underestimated risk by half.”

As for Iksil himself? He was fired shortly after the incident but may have reached an agreement with federal authorities to avoid criminal prosecution, The Wall Street Journal reported in 2013.

2. Google trainee makes $10-million dummy advert

Ever experienced a rough first week on the job? It probably wasn’t this bad.

In 2018, an employee at Google pressed the wrong key during a training exercise and put up a blank yellow rectangle on a "huge number" of sites across the U.S. and Australia for around 45 minutes, reported the Financial Times.

The trainee allegedly placed orders at “as much as 10 times the normal market price for the adverts,” costing the tech giant an estimated $10 million.

It's unclear what happened to the employee, but employers know good help is hard to find.

1. Missing comma costs Lockheed Martin $70 million

Lockheed Martin issued a contract to a customer with a missing comma — in the sale price.

The customer held the aerospace company to the offer, costing Lockheed Martin $70 million for a C-130J Hercules aircraft in June 1999.

This wasn’t the only expensive mishap of that year. A few months later, a simple math conversion error involving both Lockheed Martin and NASA resulted in the loss of a $125 million Mars probe.