Bank lost more than $225 million in minutes after an employee made simple typo

A simple faux pas ended up costing a investment banking firm a heck of a lot of money.

If you're anything like me, then you'll know diddly squat about the stock market and how it all works. However, the process of selling a certain amount of stock for a certain amount of money is pretty simple to follow.

For example, Tesla stock is currently going for $321.22 as of today (November 11), while the market summary for Amazon is currently at $208.18.

Rewind back to 2005, and Mizuho Securities Co. wanted to sell 610,000 shares for one yen. Obviously, this was a huge bargain, even 19 years ago, but it turns out it was a mistake, and that the firm actually wanted to sell one share of employment agency J-Com Co. at 610,000 yen.

Whoops.

Adding insult to injury, the number of shares in Mizuho's order was 41 times that of J-Com's true outstanding amount. However, the Tokyo Stock Exchange processed the order anyway, reported CBS News.

The firm had tried to cancel the incorrect share sale, but failed to do so.

The mistake ultimately cost Mizuho Securities Co. 40.7 billion yen (around $250 million at the time).

An unnamed employee at Mizuho Securities Co. cost the firm millions of dollars (Getty Stock)

Japan's Financial Services Agency quickly launched an investigation into the matter to see what went wrong.

Economy and Banking Minister Kaoru Yosano told reporters at the time of the incident: "In order to maintain the credibility of the Tokyo Stock Exchange, I very strongly want this issue to be resolved quickly.

"The first thing for the Financial Services Agency to do is to determine what happened in detail. Based on that, we will decide what is needed based on the rules and regulations."

With the mistake in mind, a Japanese court later ordered the Tokyo Stock Exchange to pay Mizuho Securities a whopping 10.7 billion yen in compensation after admitting that a system fault prevented a trader from canceling the erroneous share sale, BBC News reported in 2009.

The company were later compensated by Tokyo Stock Exchange (Getty Stock)

While this error didn't work out in anyone's favor, one man found himself substantially richer after an electronic trading platform seemingly deposited more than $89 million into his bank.

Daniel Levene woke up one morning to find the large sum of money in his account and thought that he'd unknowingly won the lottery.

But instead of spending the cash as quickly as possible, the good samaritan contacted E-Trade Financial Corporation (the firm who sent him the money) to flag what had happened.

As Levene suspected, the money being put into his account was an accident and the cash was taken off him.

Surely he should have been able to keep some of the money for being honest?