Bonds have benefited from the plunge in commodities. Several bond ETFs have rallied to the highest levels in months. Rising bond prices are pushing bond yields lower. And that may be a warning for stocks. That's because bond yields (which are a barometer of economic strength) have been positively correlated to stocks. The chart below, for example, shows the S&P 500 bars and the 10-Year T-Note Yield (green line) moving up together until April. Since mid-April, however, bond yields started dropping and have now fallen to the lowest level in five months. That divergence between falling bond yields and rising stocks isn't likely to continue. If bond yields are falling because of fears of economic weakness, that should start to pull stocks lower as well. My morning message today also showed some other technical divergences on the S&P 500 which are warning signs. I also wrote recently that the type of sector rotation we've seen since April out of energy and basic materials and into defensive groups like consumer staples, healthcare, and utilities is usually associated with a market correction.