Monday one analyst predicted there is up to 50% upside in a select group of steel stocks. On Tuesday, a different analyst is looking for big upside in airline stocks.

Analysts at Atlantic initiated coverage on a number of airline stocks, including a new overweight rating on Delta Air Lines (DAL) and United Continental (UAL) . The analyst assigned a price target of $68 to Delta, implying upside of roughly 30%, and a price target of $100 on United, implying upside of more than 28%.

Both stocks are higher in premarket trading, with Delta shares up 1.26%, to $53.17, and United shares up 1.28%, to $79.64.

The Atlantic analysts also assigned Southwest Airlines (LUV) with a neutral rating, but their $71 price target implies upside of about 16%. American Airlines (AAL) was the analyst's lone underweight assignment. However, their price target of $56 still suggests that approximately 13% upside could exist.

Ironically though, each of these stocks have something in common: Warren Buffett. That's right. Buffett, who notoriously avoided stocks in the airline industry, is long each of these stocks at Berkshire Hathaway (BRK.A) (BRK.B) .

TheStreet's Jim Cramer also called Southwest "the best" airline to own. Notably, Cramer, the manager of the Action Alerts PLUS portfolio, is long Southwest in the AAP portfolio.

Many investors have warmed up to the airline industry thanks to more efficient flight routes and profitability, low valuations and falling fuel prices -- the airlines' largest input cost.

More Noteworthy Ratings Changes

EQT Corp. (EQT) was upgraded to outperform and assigned a $70 price target at BMO.

Goodyear (GT) was upgraded to buy at Jefferies.

Marvell Tech (MRVL) was upgraded to overweight and assigned a $22 price target at Pacific Crest.

Nvidia (NVDA) was upgraded to sector weight at Pacific Crest.

Rice Energy (RICE) was downgraded to sector perform and assigned a $25 price target at RBC.

Rice Midstream Partners (RMP) was downgraded to sector perform and assigned a $21 price target at RBC.

This article is commentary by an independent contributor. At the time of publication, the author held no positions in the stocks mentioned.

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