It was embezzlement and bribery iirc. I doubt SM's shareholders (which might have included institutional investors like pension funds) would think it was fine for Lee Soo Man to steal from them.
I was under the impression that he was trying to inflate the value of his own stock price by purchasing his own stocks using a different company to give SM more capital which is why I wrote that (I have no idea where I manufactured that idea in my head). I didn't realise it was embezzlement which is a lot worse than that.