Santoli: The big question facing investors today

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The abrupt jump in bond yields around the world last week has challenged a core premise of the investment scene and forces this question: "Is the ultimate low in interest rates finally in the books?"

The most honest answer is, nobody knows, and it's even a bit premature to venture a confident prediction.

While the 10-year Treasury yield is up decisively from a July low of 1.36 percent, rising to 1.67 percent amid growing anxiety about central-bank intentions, it remains below where it traded before the U.K.'s June 24 vote to depart the European Union - and well beneath the 2.27 percent level where it ended 2015.

Still, the sell-off in bonds has been global enough and comes from such extreme levels that it's worth running through the sentiment, policy and fundamental factors that could determine whether this is a fleeting backup in the cost of money, or the end of the powerful 35-year trend of lower rates.

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