** Cytokinetics' CYTK.O shares down 3.3% in extended trading to $48.10 as biotech firm looks to raise capital
** South San Francisco, California-based CYTK announces private offering of $550 mln 6-yr convertible bonds (CBs)
** Co plans to use net offering proceeds to support potential commercial launch of its heart disease drug, aficamten, expand the drug's development program, among other uses
** It also intends to use portion of proceeds to issue shares in exchange for a portion of its outstanding 3.5% CBs due 2027 in negotiated transactions
** On Sept 2, CYTK shares soared ~40% to close at $49.62 after co said aficamten outperformed standard-of-care treatment, metoprolol
** Co has roughly $6 bln market cap, based on ~119.7 mln shares outstanding
** Shares on Tues ended up 0.6% at $49.76, up nearly 6% YTD
** Of 20 analysts covering CYTK, recommendation breakdown is 16 "strong buy" or "buy" and 4 "hold"; median PT is $74, per LSEG data