The 'economic expansion' is an artifact of the Fed pumping free money into the system, which had no place to go but stocks since capital appreciation was both sheltered and the only fungible investment with any return worth reaping. Raising a corporation's capital valuation really doesn't do shit for the corporation unless they issue new stock or sell existing stock being retained by the corporation itself, appreciation of stock being held by third parties only benefits those third parties. Sure, there is an effect that makes it easier for them to borrow more money, but the actual non-paper assets they control, except for intellectual property, do not become more valuable when stock held by third parties increases. It is a cloud-castle, a construct, without substance to the actual strength of the economy.
Throughout that time real wages and median income has fallen, which is the actual basis for most of any claimed 'Productivity increase' after three rounds of quantitative easing are fully discounted from the numbers.