The chart is self-explanatory. I'm not saying these two will cross, but so long as they converge, it is a good sign to be long MPC. The stock itself is oversold. It has lost half it's market cap since early Dec. Since free-falling, it has found a nice bottom at $29.
Buying MPC in the low 30S and holding until April could bring us closer to the $55-70 valuation. Selling at $50 is more in line at the lower end of analysts revised expectations.
If OVX stabilizes, and SPX decides to capitulate, overlay MPC with the S&P, and you'll find that this stock has historically bucked the market.