Thanks for the links and the response. If I may, I do still think there are a couple of tricks to watch out for, though.

The measure of leverage I am using is debt to enterprise value. There are certainly other measures, and some of them will tell a different story. But, I don't think the Wall Street Journal measure is useful. As they point out, some of the debt is related to tax arbitrage. Net debt would be more appropriate, I think.

But, even more importantly, that measure is comparing the global balance sheet of corporations to the national production level of the US. So, I think it is difficult to use that measure as a signal of leverage. Mostly, it is measuring the increasingly international footprint of US corporations.

Regarding the timing of buybacks, I think we need to be careful of hindsight bias. In a market with stochastic real properties, cash flows, forward projections, and capital deployment will tend to move together as opportunity ebbs and flows. In hindsight, this would look like herdish behavior even if it simply reflected real-time fluctuations in intrinsic values.