That's a motivated take. Obviously the party and candidates which promote less regulation are preferable to the stock market. It doesn't require accusations of corruption, and it doesn't mean their opponents are wrong, either.
They also have a very short-term outlook. Deregulation of derivatives was great for the market, until it caused a massive financial crisis.
Abortion bans, book bans, trans bans, voter ID laws and so forth are regulation. It's "regulation for thee but not for me".
Republicans are not the party of "less regulation". That's another of these myths they use like "states rights" or "fiscal responsibility".
You have a very shallow understanding of economics. "Less regulation" is great if you can't think beyond next quarter. "Good regulation" is what keeps the economy healthy long-term.