A credit spread is the difference in yield between two bonds of similar maturity but different credit quality. For example, if the 10-year Treasury note is trading at a yield of 2% and a 10-year corporate bond is trading at a yield of 4%, the corporate bond is said to offer a 200-basis-point spread over the Treasury.
As credit spreads rise, it gets more and more difficult to finance buybacks (credit conditions are worsening). Yields on corporate bonds go up (which coincides with a credit spread rise), which means that debt issued by the company (to buy back its own shares) has a higher interest rate. The result is that there will be less buybacks. There is a lag of 3 months (we borrow and then we spend).
Investment Grade Credit Spread Vs Buybacks |
So you could have predicted black monday in August 2015 (red graph) by looking at the rising credit spreads (blue graph).