Is it LEGAL to transfer enterprise's equity via stock market?

I have recently acquired an airline. I wonder whether it is considered as cheating if I transfer it's equity via stock market. Basically it works as buying and selling the shares of a 3rd party enterprise back and forth between the enterprise and the holding. In the end I can get the entire equity of the enterprise by only spending half of it to be the main shareholder (and I may even be able to sell the leftover worthless shares to someone don't know anything about all these things for more profit).

Since none of the game rules explicitly forbidden such the behavior (actually none of the game rules even talks about anything like this), will I walk away safely after doing all these things? If you think I will be considered as cheating, which line of the rules exactly am I breaching?

Here is the rules: http://otto.airlinesim.aero/app/info/rules/general?10

Please note that none of these is involved with multiple accounts that sort of thing. I have a strong intention to play the game without breaching the rules. It is kind of lucky for me when I found an enterprise whose main shareholder that held 80% at that time decided to sell the majority of his shares (and he seems to be an inexperienced player who regretted this immediately after I became the main shareholder).

Apologize for my English. I hope it all make sense.

When you buy/sell shares within your own group, the shares are always traded at the current value. You cannot trade at +/- 10%.

If you trade with a (willing) 3rd party, you both are cheating and you will get sanctioned.

(and he seems to be an inexperienced player who regretted this immediately after I became the main shareholder).

If that's the case you could also be friendly and simply sell the airline back to him.