John Paulson misplaced some. Mark Zuckerberg and the Blankfein family did, too.
Locked in various state comptrollers' vaults are billions of dollars that are owed to millions of people, ranging from the average Joe to Wall Street heavyweights like hedge fund manager Bill Ackman and former Citigroup CEO Vikram Pandit.
By law, businesses including banks, insurance companies, utilities, investment companies, are required to turn over inactive accounts to the applicable state after a dormancy period. In many states, the comptroller's office then serves as the custodian of this money until the person, person's heir or business comes to claim it.
New York State Comptroller Thomas DiNapoli oversees about $12.5 billion in unclaimed funds from more than 30 million accounts. The state operates a searchable website for the lost accounts but does not usually proactively try to contact owners of the missing funds, nor does it list the exact dollar amount of the lost funds.
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"A celebrity or a wealthy person doesn't get any special treatment because of that," DiNapoli said.
This means that even though a quick search can determine that Giorgio Armani once owed former BofA executive Sallie Krawcheck some money or that Morgan Stanley is entitled to funds once held by a slew of businesses, including Goldman Sachs, JPMorgan Chase and AT&T, neither will be getting a phone call from the comptroller's office any time soon just because they're well-known.
Since large businesses take part in many transactions, they often forget to tie up every loose end, but many periodically check unclaimed funds sites to file claims. Unclaimed accounts frequently result from moves, bankruptcies or deaths of individuals. Several casualties of the financial crisis, including Lehman Brothers and Bear Stearns, have numerous entries.
"I think the most common reason would be mobility," said DiNapoli, about why accounts become unclaimed. "People move and may not keep their contact information up to date so when the bank is trying to contact them, they can't find them if there's no forwarding address."
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Although about half of New York's claims are for amounts less than $100, much larger sums currently lurk in accounts. More than $1.7 million sits unclaimed in one individual's account.
How exactly does someone fail to notice such large missing sums? Well, it's happened before.
In the past year, Florida's chief financial officer, Jeff Atwater, was able to return a fund worth about $1.1 million, a case where money passing from generation to generation became lost along the way.
Atwater oversees more than $1 billion in unclaimed accounts and property from abandoned safe-deposit boxes. Often, these high-dollar accounts contain more clues for tracking down their owners.
"We proactively try to find people for any amount, but there is typically a greater likelihood that there would be a chance to reconnect with someone because the institutions providing this had a little more information," Atwater said about bigger accounts.
No matter how much time has passed, states will return the funds at no charge or for a nominal handling fee once the rightful owner or heir files a claim. For unclaimed tangible property found in safe-deposit boxes, many states also hold periodic auctions, the proceeds of which will be held for owners to claim.
These items can range in value from a bag of diamonds, estimated to be worth $500,000, to a 86-cent can of sardines being held by the California controller.
Until the funds are claimed, states use some of the money to fund various government programs.
To get the word out, states hold workshops detailing how individuals can search for missing funds. In New York, the unclaimed funds office will also perform periodic searches in areas that they plan to hold events to serve as examples of successful claims.
"A couple years ago in the Syracuse area, in connection with the state fair, we were able to locate someone who had $10,000 owed to him," DiNapoli said. "What made the story memorable is he was in the hospital, had just been discharged and had some pretty significant medical bills."
After the devastation of Super Storm Sandy last fall, the office also made a point of reaching out to those communities hard-hit by the storm.
"Certainly when we see a great need like that, we don't want to be in any way sitting on people's money," DiNapoli said.
These outreach efforts and the online search tool have made it easier to find the funds and fueled a rise in the amount of money being returned as people continue to go through tough economic times and need the money, he added.
Florida's Atwater advises everyone to take a peek. "I want everybody to look—you just don't know, and you might not suspect it," he said.
On second thought, maybe he's got things higher up on the to-do list.
—By CNBC's Katie Little. Follow her on Twitter @KatieLittle.