Keeping indexes in check was GE Aerospace, which tumbled 9% and was the heaviest weight on the S & P 500. The company, which began trading independently this spring after splitting off from the former conglomerate General Electric, reported stronger profit for the latest quarter than analysts expected, but its revenue fell short of forecasts.

U.S. stocks are slipping again as Wall Street’s record-breaking rally loses more momentum. The S&P 500 was 0.4% lower in Tuesday morning trading and on track for its first back-to-back loss in a month and a half.

Last week, RBC Capital's Paul Treiber boosted his fair-value assessment of Shopify to $100 per share, well up from his preceding level of $85. In doing so, he maintained his outperform (read: buy) recommendation, as the new price target sits a comfortable 21% over the stock's most recent closing price.