Investors don't think the safest bonds of all are a sure thing anymore

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• With deficit concerns swirling, the market for the safest government bonds has been volatile.
• Bloomberg reported on Monday that top fixed income firms are staging a "buyers' strike."
• Investors are hesitant to buy bonds with long maturities amid doubts about the US fiscal position.

A corner of the ultra-safe US Treasury market is losing its shine amid concerns about America's long-term fiscal health.

It's an increasingly worrisome...