I would say his plan to rebuild the US ' s infrastructure has a lot more to do with the market going up than tax cuts . The US is estimated to need $ 3 bil to rebuild its infrastructure and Trump also said he wants to use American steel and materials to rebuild the country . I would also say that savingsinvestment is more dependent on interest rates rather than tax cuts . Higher rates put your money in banks for guaranteed safer returns , Lower rates put your money in the market for risky higher returns . Anybody who had their money in banks when the Fed cut its interest rates to near zero was making a poor investment decision . You wouldn ' t have made any money to keep up with inflation and the stock market boomed within that time .