NEW YORK (TheStreet) -- The relationship between stocks and bonds is a useful way to gauge investor sentiment. Those two markets tend to have a negative correlation most of the time, but not always.The debt market dwarfs that of equities. (Most people assume the stock market is larger.) So many times during intraday trading, I can "see" the tug of war between bonds/notes and the S&P 500. More often than not, I will side with the bond market because, in my experience, bonds tend to be "right" more often. Not only can monitoring these types of correlations help with intra-day trading, but they can also be useful for longer-term traders and buy-and-hold investors. Current market conditions are a prime example. Although the S&P 500 has been holding around the 1,400 handle and bonds are off recent highs, the December 30-year bond futures have held an uptrend line when they bounced off the 150 handle on Friday's and Monday's sessions.