Stock market measures two things, 1) the performance of firms within their economic environments. 2) the level of savings to be invested in the stock market.

Both are tied to the labor-share of income. That is, how much income is generated through yield on capital (firm profits returned to shareholders, rents, financial services) compared to earned through labor.

This chart inversely correlates nicely with the stock market. https://fred.stlouisfed.org/series/W270RE1A156NBEA