The most vulnerable group in this selloff it is the natural gas contingent. The price of natural gas has been cut in half and then cut in half again from its high. I do not know how many of these big natural gas companies -- Chesapeake (CPK), Anadarko (APC), Southwestern Energy (SWN), Cabot Oil & Gas (COG), Ultra Petroleum (UPL), XTO Energy (XTO) and Devon (DVN) -- can make their earnings with natural gas at $3.60/MMBTU and going lower because of the end of the winter heating season. We are at six-year lows, but the incredible commodity declines shows me that there are still speculators trapped in natural gas that must liquidate positions. Many of these stocks last week rallied on the hopes of a new wave of consolidation, kicked off by the purchase of Petro-Canada (PCZ) by Suncor (SU). I am dubious at the prospects of mergers in the big American natural gas players mostly because of the dominant personalities of the people who run these companies. They are fierce competitors and huge believers in their companies -- consider all of the stock that Aubrey McClendon had to sell because he used so much money to buy stock on margin. At $3.60, many of the new plays on natural gas could be marginal. Plus the big nat-gas land grabs from two years ago now feel downright foolish. Everyone's justifiably worried about first-quarter earnings given the world economy's huge downturn. The cohort with the biggest risk is this one, and the rally has brought many of them to unsustainable highs. I would be a seller of every one of these stocks. If you want exposure, pick an integrated with a dividend like ConocoPhillips (COP) or Chevron (CVX). Even these are too risky after huge runups.

From a recent Mad Money show:"Here's a stock that's almost doubled. That says to me, sell, sell, sell. Let's take profits in Whole Foods."

From a recent Mad Money show:"The stock is up on a spike this week. I think it can retreat a buck and a half, let's wait to buy more."

From a recent Mad Money show:"I think Marathon is a buy. I think you wait until $25, then buy, buy, buy."

From a recent Mad Money show:"People are concerned with the balance sheet and I am, too. You have to lighten up on that position."

From a recent Mad Money show:"People regard this too cautious and safe. I'd used the flatlining to pick some up. I want to buy, buy, buy."

From a recent Mad Money show:"I think Denbury is an inexpensive mineral company. I'm a buyer, that one used to be twice as high."

From a recent Mad Money show:"I think this is the best of the group, except for Terra Nitrogen (TNH) with the great dividend. Monsanto is my number two pick in that group."