Questions on market rules

I'm fairly new to this game but have made quite a pretty penny off of the market board, then I remembered certain games have rules about abusing the market too much. Are there any such rules here?
Examples of market board abuse would be:
1) Buying up all stock (one specific item type) below a set value and relisting them all at your new value, save maybe 1 or 2 listings to avoid paying the 5% market charge and maxing profits
2)buying up large stacks splitting and selling at higher then market value, thus taking advantage of smaller buyers and letting the whales buy bigger for less
3)generally anything which counts as total market control strategies such as permanently sitting on 1 or 2 items maintaining their prices nearly indefinitely at your set price

As stated above, are tactics like this "illegal"? Thank you in advanced for any helpful replies (PS. Asked because I couldn't find any other forums stating an answer to this, from Square enix, or third party forums):D

None of that is illegal in the sense of being against the game's TOS or something that the game would stop you from doing. Depending on how active your world's economy is, you may end up either upsetting people or having a hard time keeping it up depending on what you're trying to manipulate. (Balmung has lots of people active in the markets, for example, so controlling the market on anything that's in high demand is a tricky proposition.)

Buying stacks and reselling smaller quantities can even be helpful to some people.

There's nothing against the ToS for any of those things, but they all have their drawbacks and risks:

1 - With limited MB slots, people rarely have their entire stock of a money maker listed, so while you think you're buying it all up, they just relist more.
2 - Good practice, just make sure you check how many are needed for what people use them for and sell too small or odd quantities. If a recipe takes 9, sell in stacks of 1 or 9.
3 - If you're making a good profit, there's always going to be someone out to undercut you.

Thanks for the responses, and allright.... Also I don't mind undercutting, the markets i usually try and use like that are gathered resource markets, so even though it hurts bigger fish, the smaller newer players myself have easier access to revenues through gathering and such... my own opinion on that, and if they undercut too much well its just more stock for me! =)

Timing is key also. Thursday evening is the best to buy things for cheap. People will undercut all week long from Monday to Thursday. Then relist them at a higher price on Friday evening when all the weekend players get on.