Refining margins in the Rockies (West Texas Intermediate) fell the most among the five U.S. petroleum districts, by $4.40 a barrel to $28.44 in the week ended Sept. 25, Credit Suisse said in a weekly report on Wednesday. Margins in the West Coast (Alaska North Slope) were down $3.02 a barrel to $15.35, followed by the East Coast (Brent) margins, which fell 22 cents a barrel to $9.01. Meanwhile, Midwest (WTI) margins were up $3.80 a barrel to $22.30, followed by the Gulf Coast (Light Louisiana Sweet) where margins rose $3.38 a barrel to $11.13. (Reporting by Harshith Aranya in Bengaluru; Editing by Anand Basu)