If it's worth saying, but not worth its own post (even in Discussion), then it goes here.
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It exists but it's noisy. US Treasuries are more a bet on interest rates (i.e. monetary policy) than on actual growth; CDS is more about the possibility of a technical default caused by political brinkmanship than about the US genuinely running out of money. Based on a quick internet search, the S&P 500 is only very weakly correlated with GDP. Commodity prices are more about expectations for that commodity, foreign exchange rates are inseparable from the foreign country involved.