I saw that 25 million shares traded a few days ago in the stock. Was there a corporate event involved? I couldn't find anything. I then looked at the option chain and saw that 10,685 July $12.5 Puts were open (8,191 puts traded at $0.30 on 6/24 and $1,843 traded at $0.40 on 6/25, same day as the 25 million shares). Today ARCC closed at $12.53, just above the the put strike.
I found a great article on the put action at The Options Insider called: Ares Capital (ARCC) - Huge Downside Put Buyer on "Mezzanine Debt" Holder. The author mentioned that an institution could be hedging. Something is up. Watch downtrend resistance and the $12.50 level. For more information I found a blog that tracks the BDC industry.
ARCC (Ares Capital) - FreeStockcharts.com