This method had been used for a while by RMT and Non-RMT game breakers. It involves lot of peole but since it had proven extremely effective and possible. People had been complaining that they filed reports to GMs and they stated that this is not against Terms of Service, so enjoy it while you can.

Now starting with AH basic. When you check the price history, you will see that there are ten previous transactions available as a referrence. This is how it is done, the more people you have, the better. But a full party should do.

Assume that we are going to crash the price of "X" and history page for "X" is as following.

Seller1 > Buyer1 50
Seller2 > Buyer2 55
Seller3 > Buyer3 49
Seller4 > Buyer4 50
Seller5 > Buyer5 50
Seller6 > Buyer6 50
Seller7 > Buyer7 49
Seller8 > Buyer8 49
Seller9 > Buyer9 50
Seller10 > Buyer10 50

Now assume you and 5 of your classmate are playing FFXI all togather and want a lot of Gil to finance your private LS's K.Club. And assume that names of participants are as following.

You
Dude1
Dude2
Dude3
Dude4
Dude5

Your group will have to possess a copy of "X", how to obtian it? Figure that out by yourself. Start by You and Dude1 standing in front of the AH at the same time to prevent possible losses. Place your "X" on AH at the price of 1 gil and have Dude1 bid it out at, say, 35 gil instantly. Now, the AH history page will show up like this:

Seller2 > Buyer2 55
Seller3 > Buyer3 49
Seller4 > Buyer4 50
Seller5 > Buyer5 50
Seller6 > Buyer6 50
Seller7 > Buyer7 49
Seller8 > Buyer8 49
Seller9 > Buyer9 50
Seller10 > Buyer10 50
You > Dude1 35

Go mow your lawn have lunch, do your homework checking ###### website or whatever you want, I don't really care. Come back and check the history of "X" again. If there is no transaction try bid "X" at 35 for next few hours. If it is not working then switch people and do it again. Until the History page looks Similar to this.

Seller4 > Buyer4 50
Seller5 > Buyer5 50
Seller6 > Buyer6 50
You > Dude1 35
Dude2 > Dude3 32
Dude4 > Dude5 36
Dude1 > You 36
Dude3 > Dude2 32
Dude4 > Dude1 31
Dude5 > You 30

If it doesn't working, move on to something else, my advice is something that people usually buy in pair. But if it works, in next few days, history page should appear like this:

Dude1 > You 36
Dude3 > Dude2 32
Dude4 > Dude1 31
Dude5 > You 30
Loser1 > You 30
Loser2 > Dude1 31
Loser3 > Dude2 32
Loser4 > Dude5 31
Loser5 > Dude4 30
Loser6 > Dude3 30

Your group will now possess majority of "X" flowing in the market. Now reverse everything you do and in the end the AH should looks like this:

Loser5 > Dude4 30
Loser6 > Dude3 30
You > Dude1 65
Dude1 > Loser7 63
Dude3 > Loser8 64
Dude4 > Loser9 60
Dude5 > Loser10 62
Lucky guy > Unlucky Guy 60
Dude2 > Another Loser 62

When the market of "X" dies, move on and prey on something else.
It had been done, it works and it is not against ToS.

Hope ull find this useful

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This is not a cheat.

Also it is quite risky. You could invest a lot, and ultimitely fail and be left with a bunch of "X" that you can't move at the prices you're setting.

Also sites like ffxiah.com will allow you to see more than just the last 10 transactions, making this harder to pull off.