Magento, which counts CocaCola Co, Intelligentsia Coffee, Canon Inc and Burger King among its customers, helps companies build online stores, competing with Shopify whose software and consulting expertise helps merchants sell everything from infant formula to cosmetics online.

Analysts said the deal gave Adobe, best known for photo-editing suite Photoshop and PDF reader Acrobat, greater exposure to the digital commerce industry and posed a threat to Shopify's "Plus" larger-scale enterprise solutions.

"We see the Adobe/Magento combination as a new long-term threat for investors to consider as Shopify continues to target larger merchants," Brian Essex, analyst at Morgan Stanley wrote in a note.

Shopify shares fell as much as 5.5 percent on Monday after market when Adobe announced the Magento deal. Premarket trading projected them to fall 1.8 percent at opening in New York on Tuesday.

The firm's main Toronto-listed shares will not begin trading until the stock market there opens at 9.30 a.m. et. Adobe shares were broadly unchanged from the previous close in premarket.

(Reporting by Laharee Chatterjee in Bengaluru; editing by Patrick Graham)