Are Asset Classes Correlated?

Bond yields and stock prices are said to be inversely correlated. This means that an investor looking to buy equities, can get a confirmation via reducing interest rates.

Look how beautifully this has played over the long term in the US stock market returns and US Bond Yields.

Similarly, bond yields and commodities are positively correlated due to the common factor "Inflation" influencing both of them. 

Notice how both CRB index (an index that tracks major commodity prices) has risen along with the bond yields. Hence an investor looking to buy commodities, can get a confirmation via looking if the bond yields are rising or not.