** Shares of Australian engineering firm Worley WOR.AX rise 8.6% to A$15.220, their highest level since May 9, 2024

** WOR rises as much as 11.6% in early trading, marking its biggest intraday pct gain since June 9, 2020

** WOR is the second biggest gainer in the ASX200 benchmark index .AXJO

** Company says it will undertake an on-market share buyback of up to A$500 million ($317.45 million)

** Posts 1H25 underlying NPAT of A$216 million, up 15% from last year, slightly below the Visible Alpha consensus of A$219.6 million

** Reaffirms FY25 outlook of targeting low double-digit EBITA growth, compared with 24% growth in FY24

** Jefferies says: "outlook comments point to slowing pace of energy transition work that may affect consensus FY26+ expectations of double-digit revenue growth"

** Mixed outlook, but confidence in delivery of FY25 guidance, says Jefferies

** WOR up 12.9% this year, including the day's move

($1 = 1.5751 Australian dollars)

(Reporting by Sameer Manekar in Bengaluru)

((Sameer.Manekar@thomsonreuters.com))