Most money ever wagered on a single bet?

Anybody know what the most money ever documented to have been put down on an even money* bet is? For this purpose I mean a bet to be where one party says “X is the Case”, the other says “X is not the case” and they use money to back up their words, not things such as investing in derivatives/stocks et cetera. 1 to 1 gambling activities with a definitive outcome, like a single hand of Blackjack or a single spin at Roulette would be acceptable.

*not necessarily even money, but in a bet with odds, the guy putting the least on the table is the figure that counts

When Australian racehorse Lonhro had it’s last start in 2004 Aussie bookmaker Michael Sullivan of *Sportingbet *took a bet of $5,000,000 from one punter to win $1,000,000.

Lonhro ran second.

Kerry Packer wagered around $100 million over the Spring Racing Carnival, He was rumoured to have won either $20, $30 or $40 million at the Las Vegas casinos over a few days in 1997.

This doesn’t help with one large bet. However, it gives an indication of how the wealthy can gamble.
Kerry Packer.

Here is a more accurate account of Kerry Packer’s gambling from his Paul Barry biography.

My favourite story was the previous biggest single documented bet in Australia - his $3,000,000 on Myocard in the Sydney Cup to win $2,000,000. Myocard didn’t run a place and the race was won by Major Drive owned by Kerry Packer.

Press coverage made most people think that Packer was a big winner gambling. The truth was he pissed away millions of dollars.

I once bet my brother “all the money in the world” that he couldn’t juggle 4 eggs.

Last November two guys played an online poker game in which the biggest hand had a pot of $1.3 million.

You could say it was the final hand of the 2006 World Series of Poker. When both Jamie Gold and Paul Wasicka put all their chips into the pot they were betting $5.9 million, the difference between the $6.1 million second place and $12 million first place payoffs.

Advance nit picked: Yes, it’s true that things were murky a bit since Gold would have had chips left if he had lost the hand, and yes, it’s true that their individual equities in the pot varied a bit due to their different chip holdings … still, it basically amounts to a bet for $5.9 million on the turn of a card.

It’s not as big as some of the others mentioned upthread, but one of the most publicized bets was one covered by reality tv show “Double or Nothing”. A guy sold everything he owned and bet it all on one roll of a roulette wheel. He turned his $135,000 life’s savings into $270,000 on one spin. I didn’t see the show, but I remember reading it on the news.

A hard-charging hotshot at the Salomon Bros. investment firm on Wall Street in the Eighties offered a $1 million bet to a coworker as to the serial number of an otherwise-unremarkable dollar bill, IIRC, in the book Liar’s Poker by Michael Lewis, but the coworker turned him down.

Another bet not quite in the spirit of the OP, but an Australian syndicate examines the odds of lottery wins around the world and buys up a significant percentage when it sees the odds are in their favour. Several US State lottery boards have changed their rules based on their business model.

But my google-fu fails me when looking for a cite.