It's been a wild ride for long-term Treasury ETFs lately, and it's looking like they might have hit a rough patch. Following months of declining interest rates, yields on U.S. Treasurys reversed course in October, and the charts are now flashing a warning: the dreaded Death Cross is looming.

For those who aren't familiar, the Death Cross occurs when the short-term moving average (such as the 50-day) crosses below the long-term moving average (like the 200-day).

And that's exactly what's been happening for a trio of heavy hitters in the bond...