NEW YORK (TheStreet) -- RATINGS CHANGES National Oilwell Varco was downgraded to hold at TheStreet Ratings. You can view the full analysis from the report here: NOV Ratings Report. Stone Energy was downgraded to sell at TheStreet Ratings. You can view the full analysis from the report here: SGY Ratings Report. Editor's note: To see analysts' stock comments and changes to price targets and earnings estimates, go to "Street Notes," which is available only to Real Money subscribers.