This article was published by Harvard Business Review just before COVID crashed global markets & caused both the US & all major gov’ts & central banks to hit the nuclear button & flood the financial system with excessive liquidity, stimulus, & zero interest rates (that remained there for wayyyy too long), but holds even more true today than it did back then. Only difference is all that stimulus & free money only made the buy-back bubble much bigger. The piper will ultimately get paid, he always does:

https://hbr.org/2020/01/why-stock-buybacks-are-dangerous-for-the-economy

100% a (net bullish) contributing factor. The bigger picture regarding the trend in the stock market is all about liquidity (the massive fiscal & monetary stimulus from COVID still sloshing around but will eventually dry up) and jobs (consumer spending ~70% of GDP).

A vicious cycle, really: When the jobless rate is near historic lows, as it has been recently, people spend $. When people spend $, companies’ profits rise, when their profits rise, they plow some of that extra (found) $ into stock buybacks.

When the employment cycle bottoms & starts to turn, all that happens in reverse, including reductions & eliminations in buybacks

Keep in mind that, just like today, corp buyback were both rising AND had surged to record pace leading into the 2007 market top (followed by the Great Recession & 55%+ drops in the SPX & NDX).

Hence, the (long-term, weekly & monthly) charts are signaling that the punchbowl is likely to be withdrawn relatively (relative to those time frames) soon and that corp earnings AND buybacks will start to trend the other way when it does.