Offer your thoughts or opinion on the input financial query or topic using your financial background.

Why is Insider Trading Illegal?
To be flippant: it is illegal because it is against the law; there is no considered involved, it just is. To elaborate, part of the illusion of the stock exchange and other market-like entities is that of (apparent) fairness. If I think a stock will go up because it is involved in a growing industry, that is generally public information.  Conversely if I have a dim view of a particular company because of its track record of product launches, that is similarly out in the open. A secret formula is something that I invented or discovered, not (presumably) something that I stole from someone else. To stretch that further: If I notice that Company X stock always moves with Company Y stock, that is indeed something that I have found, that I can try to profit from.  It is secret to me, but not particularly dependent upon information not available to others, just that my interpretation is better. So trading on information in the public domain is fine, as it preserves the principal of fairness I mentioned, whereas inside knowledge breaks that principal.