** Shares of cybersecurity firm Rubrik RBRK.N, backed by Microsoft MSFT.O, down 4.7% premarket to $88.75 as it looks to raise capital

** Palo Alto, California-based RBRK offering privately $1 bln 5-yr convertible bonds

** It plans to use net proceeds to pay for capped calls, derivative transactions employed to reduce dilution, to fully repay ~$328 mln of outstanding loans under and terminate its credit agreement

** Co also intends to use proceeds for potential acquisitions or strategic investments, and working capital among other purposes

** With ~193.4 mln shares outstanding as of May 31, co has ~$18 bln market cap

** RBRK shares on Mon fell 4.9% to close at $93.15, trimming YTD gain to 42.5% YTD

** Of 22 analysts covering RBRK, recommendation breakdown is 19 "strong buy" or "buy" and 3 "hold" ratings; median PT of $110 up from $80 a month ago - LSEG latest data

** Co went public in Apr 2024 after IPO priced at $32

(Lance Tupper is a Reuters market analyst. The views expressed are his own)

((lance.tupper@tr.com 1-646-279-6380))