They figured 10% of the ad click-throughs would yield a sign-up.

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Technically, a high yield test would be self-evidently a sign of national strength.

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That is a sign that high-yield bonds look expensive, at least relative to stocks, says Edward Marrinan, head of macro credit strategy at RBS Securities in Stamford, Conn.

WSJ: Is It Time to Trash Junk Bonds?

In a sign of yet more concern, Spain's bond yield ended Monday's session higher than it was before the weekend's events, with the yield on Spain's 10-year note -- effectively the country's borrowing costs -- posting its biggest one-day jump in a year.

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When the yield curve is inverted or relatively flat, it is a sign that investors are so afraid of future economic weakness that they are willing to take low interest rates on long-term holdings for fear that returns will become even less attractive later on.

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Yet in a sign that investors remain more risk-averse to Italy, the yield on Italian 10-year bonds on Tuesday increased to 5.8% from 5.6% on Monday.

BBC: Markets volatile on fears eurozone debts may spread

In a sign of further volatility, the benchmark 10-year Japanese government bond yield hit 1.0%, the highest in nearly a year.

WSJ: European Markets Tumble

The yield on high-yield bonds has risen to 9.33%, the highest level since 2002 and a sign of growing default risk, even though defaults remain near a historic low.

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