Earlier quoted context omitted.
Not investing such a large percentage of their capital in long-duration fixed income vehicles all at once. There's nothing wrong with going long on duration, it's a hedge against decreasing rates. The problem is when you go all-in on long duration investments and rates suddenly shoot up like they did, you now can't sell those assets without eating a massive loss. An appropriate hedge would have been doing what every…
Makes me wonder why they made the risky move in the first place, they surely knew the risks, but still did it, because of greed for higher yields?
Even at the time it should have been seen as a short-sighted move, however. It was obvious ZIRP wouldn't go on forever and rate risk would bite you in the backside, so I can't call it anything but careless yield chasing without proper risk management.