"Don't fight the Fed" has been a market mantra for the past four years. But some bond investors are preparing for a change, reports the Wall Street Journal's "Abreast of the Market." Figuring that the Fed won't be able to keep a lid on interest rates forever, large money managers such as BlackRock (BLK), TCW Group, and Pacific Investment Management Co. are getting ready for the day when rates take their first turn higher. It isn't coming anytime soon, these investors say. But when it does, they worry, the rise will be swift and steep.