PREVIEW: Merck expected to post slight Q3 revenue gain, EPS decline y/y

** Shares in drugmaker Merck MRK.N were down ~1% on Wednesday ahead of quarterly report due out before market open on Thursday

** Wall Street analysts expect Merck to report Q3 adj EPS of $2.08 down from $2.68 in same quarter a year ago on rev of $17.31 billion, up slightly from $17.28 billion in year-ago qtr, according to LSEG

** In last eight quarters MRK's rev beat seven times while EPS beat every time

**In August the co reported higher-than-expected second-quarter sales and raised its full-year revenue forecast on the strength of its top-selling cancer treatment Keytruda

** YTD the stock is up ~33% vs a ~9% gain for the Dow .DJI and a 16% advance for the S&P 500 healthcare index .SPXHC

** MRK options imply a 4.1% swing for the shares, in either direction by Friday, per data from options analytics service Mercury Alerts; the stock has logged an avg move of 2.4% on the day of results over the last eight qtrs