Rambus (RMBS) is up 82 cents to $17.02 and 11,000 calls traded, compared to 1,500 puts (chart). The call volume represents 6X the expected for the first 90 minutes of trading and is focused on the Aug 17s and 18s. About 7,400 traded and about two-thirds hitting ask-side. The top trade is 712 Aug 17 calls on the ISE, which is an opening customer buyer, according to sentiment data. Implied volatility is moving up to 66, from about 61 the day before. Today’s heightened volume and volatility in RMBS comes amid renewed (and unsubstantiated) takeover chatter–Briefing.