Shares buybacks can have a severely destabilizing impact on longer term companies' valuations, as noted in numerous posts on this blog. In the COVID19 pandemic, legacy shares buybacks are associated with reduced cash reserves cushions and thiner equity floats for the companies that aggressively pursued this share price support strategy in recent years. Hence, logic suggests that companies more aggressively engaging in shares buybacks should exhibit greater downside volatility - de facto acting as de-hedging instrument for risk management.
Here is the evidence:
Note how dramatically poorer S&P500 Shares Buybacks index performance has been compared