** Utility firm Alliant Energy's LNT.O shares fall 3.5% to $59.58

** LNT announces proposed offering of $500 million of three-year convertible bonds in private placement

** Proceeds will be used to repay or refinance debt and other purposes

** Stock closed 1.1% higher at $61.76 on Friday

** LNT has 256.9 million outstanding shares for $15.9 billion market cap, according to data compiled by LSEG

** 4 of 14 brokerages rate stock "buy" or higher, 9 "hold" and 1 "sell"; median PT is $67 - LSEG data

** As of last close, LNT stock up 4.4% YTD

(Reporting by Arasu Kannagi Basil in Bengaluru)

((ArasuKannagi.Basil@thomsonreuters.com;))