The risk-off trade on Greece, China, Puerto Rico

Traders work on the floor of the New York Stock Exchange.
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Traders work on the floor of the New York Stock Exchange.

So much for a sleepy second half...

With a possible exit by Greece from the euro, Puerto Rico's governor saying it's unable to pay its debts and Chinese stocks in a bear market, the world for investors changed over a single weekend.

"Now that Greece has been caught and Puerto Rico has confessed, all the other criminals are in jeopardy," wrote Brian Kelly of hedge fund BKCM. "I don't know if we are at the beginning of a systemic debt domino effect, but if we are, I would expect to see multiple confessions over the next six-12 months."

The CBOE Volatility Index—the market's fear gauge—lost a quarter of its value until last week, when it started to creep higher into the weekend. The measure was up more than 15 percent in early trading Monday.

So if we're in for period of sustained volatility in the second half of the year, here's how to batten down the hatches.