** Electric utility NRG Energy NRG.N shares fall 4.3% post-market to $168 after secondary offering launched
** Houston, Texas-based NRG says affiliates of LS Power to offload 12.3 mln shares
** Shares part of the consideration selling shareholders received from NRG in recently closed acquisition of LS Power's natgas generation facilities and a virtual power plant
** Barclays and Citigroup joint bookrunners for offering
** NRG has ~214.7 mln shares outstanding
** Stock on Mon closed down 1.9% at $175.58, up 10% YTD. Stock hit record intraday high of $189.96 last Weds
** Avg rating of 16 analysts is "buy"; median PT $203, per LSEG
(Lance Tupper is a Reuters market analyst. The views expressed are his own)
((lance.tupper@tr.com 1-646-279-6380))