I don't understand why someone would buy and sell at the same time

[Hawker]

You have a better explanation for an incentive to sell low and buy high multiple times?

Why would anyone do it that rapidly, creating a huge spread? It makes no sense at all.
My assumption is that this has to do with either IGmarkets or plus500 who offer spread betting. They can wipe out their customers easily this way, collecting money on that end, while just spending a bit on MTGox.
Another option is just a bot going nuts.

Wow - that would actually make a lot of sense.  Someone who hedged against the price reaching $116 would have every incentive to buy a ton of Bitcoin and sell at a loss to drive the price to $116 and pick up his winnings.

[evolve]

Why would you think it's the same person buying and selling?

This.

[GeniuSxBoY]

Why would you think it's the same person buying and selling?

This.

There is a variable called time that would tip you off.

[GeniuSxBoY]

You have a better explanation for an incentive to sell low and buy high multiple times?

Why would anyone do it that rapidly, creating a huge spread? It makes no sense at all.
My assumption is that this has to do with either IGmarkets or plus500 who offer spread betting. They can wipe out their customers easily this way, collecting money on that end, while just spending a bit on MTGox.
Another option is just a bot going nuts.

Wow - that would actually make a lot of sense.  Someone who hedged against the price reaching $116 would have every incentive to buy a ton of Bitcoin and sell at a loss to drive the price to $116 and pick up his winnings.

Wow, it makes no sense. As a customer, it would be too obvious to see the manipulation. And while it might maybe make sense one time, three times in a short amount of time is stupid. Even if you had 3 separate bets going, you'd only need one of those blips to win all three games.

[Babylon]

Could be bot gone wild, could also be someone that doesn't have the funds to buy anymore, thus they sell a ton, and immediately buy a bunch more in an attempt to eat through the 125 wall. They kept trying to do this and appear to have failed miserably and people just started throwing asks up to 125 and made the wall even more massive, lol.

But even if they get though 125, they have lost a ton of money on the trading fees.  How can they actually make a profit on selling at 124, buying back at 119 and then doing that repeatedly?

A $5 spread is going to make money, not lose money.  That's 4% profit, even if the trading fees are at their highest they are only .6% one per trade means 1.2% in trading fees so the trader is making 3.8% profit.

[Hawker]

Could be bot gone wild, could also be someone that doesn't have the funds to buy anymore, thus they sell a ton, and immediately buy a bunch more in an attempt to eat through the 125 wall. They kept trying to do this and appear to have failed miserably and people just started throwing asks up to 125 and made the wall even more massive, lol.

But even if they get though 125, they have lost a ton of money on the trading fees.  How can they actually make a profit on selling at 124, buying back at 119 and then doing that repeatedly?

A $5 spread is going to make money, not lose money.  That's 4% profit, even if the trading fees are at their highest they are only .6% one per trade means 1.2% in trading fees so the trader is making 3.8% profit.

I misspoke.  They were buying at 124 and selling at $119.  That's why I think they lost a ton of money.

[arsenische]

Imagine you have 10 btc and/or 1000 usd, and current orderbook is the following:

Volume@Bids

1@100
2@99
3@98

Volume@Asks

1@101
2@102
3@103

First you buy 6 btc for 614 usd causing 1 minute lag and preventing others from making orders, then you sell 6 btc for 592 usd, thus you loose 22 usd + fees.

Or you can do the other way around, then you will loose bitcoins + fees.

That's roughly what happened. I am not sure it is a good trading strategy.

Update: so, yes, I like the explanations that it is either a software glitch of a trading bot, or an attempt to win some bet