* Offer values Alon at about $516 mln
* Offer represents a 16 pct discount to Alon's Thursday close
* Delek says both companies currently "undervalued" (Adds background)
Oct 14 (Reuters) - Alon USA Energy Inc's largest shareholder, Delek U.S. Holdings Inc, offered to buy the smaller refiner in a deal that valued the company at about $516 million.
Delek, which holds about 47 percent of Alon USA, said both the companies were "currently undervalued." (bit.ly/2dbErMo)
A glut of refined products and steadily rising crude costs have pressured refining margins. Refiners' third-quarter earnings are expected to plunge as much as 46 percent on average, according to Morgan Stanley.
Alon owns and operates refineries in Big Spring in Texas; Paramount, Long Beach and Bakersfield in California and Krotz Springs in Louisiana. The refineries have a combined capacity of nearly 217,000 barrels per day.
Delek's refining business, which has a combined capacity of 155,000 barrels per day, operates refineries in Tyler, Texas and El Dorado, Arkansas. The company also owns a 62 percent stake in Delek Logistics Partners LP.
Delek said in August it would sell its retail assets, including a network of about 348 company operated convenience store locations, to a Chile-based company for $535 million.
Delek on Friday offered 0.44 of its shares for each outstanding share of Alon USA. Based on Delek's closing price of $16.42, the offer works out to $7.22 per share, a 16 percent discount to the stock's Thursday close.
Alon's shares were trading at $8.57 before the bell, while Delek's shares were up 5.4 percent at $17.30.
Alon's shares closed at $8.60 on Thursday, valuing the company at $614.1 million. Delek had a market value of $1.02 billion.
Delek said it would not proceed unless its offer was approved by a special committee of Alon directors, who are independent of Delek.
The offer also has to be approved by a majority of Alon shareholders, excluding Delek and its affiliates. Alon had 71.4 million shares outstanding as of July 25.
Tudor Pickering Holt & Co is Delek's financial adviser for the Alon deal and Norton Rose Fulbright US LLP its legal counsel. (Reporting by Arathy S Nair and Anet Josline Pinto n Bengaluru; Editing by Don Sebastian)