I don't think that tax cut went into the stock market. Return to low, slow.
The stock market has some regulation, some oversight, and a limit on how much credit (margin) can be extended.
I think a large proportion of those cuts formed the 10% down paid on the "highly (90%) leveraged" derivatives. Unregulated, promising much higher returns.
And according to Conservatives, thereby stimulating the economy and creating new jobs.
Arf