Immediate sugar high from lowered taxes.
Decline when incremental GDP is invisible and debt increases, (thereby proving the point for the hundredth time that you are only likely to improve GDP when lowering extremely high tax rates, and you increase risk when you reduce or remove protections).
And so we have wasted again a steady-as-she-goes economy, this one produced by Obama, in return for rewards for the wealthy from the party of the wealthy, supported by the low information rubes who get the recession which follows.
Not that a recession is guaranteed. Stock markets and economies aren't entirely correlated. But Trump is doing the sorts of things which make them happen, such as trade wars, investing in old and expensive sources of energy, not paying expenses and abusing the Fed, upon whom the market relies.