Shares of Shopify (SHOP) - Get Report were falling after analysts at Guggenheim downgraded the stock and eliminated their price target, as the stock has soared in 2019. 

The stock of the e-commerce platform provider was falling 4.67% to $246.83 a share Monday. It's up 83% this year. 

Guggenheim downgraded Shopify to Neutral, and removed its price target, which was last pegged at $285, as the stock is moving closer to what Guggenheim deems fair value. "We believe bullish investors have already embedded a revenue outcome for FY19 and FY20 consistent with historical beats to consensus," analyst Ken Wong wrote in a note out Monday morning. "The valuation multiple has surpassed previous peak levels (~16x NTM EV/Sales vs. 14x) which we believe limits share appreciation from delivering results that significantly outpace street estimates." 

Wong moved his estimates up slightly to reflect the best-case scenario for 2019 and 2020, as his revenue estimates are now $1.65 billion and $2.4 billion, respectively. "Valuation at those "upside" levels (11.5x CY20) is approaching fair value," Wong said. 

Since Wong believes Shopify's business model doesn't justify a higher enterprise value to sales multiple, "share appreciation will need to come from upside to estimates," he noted. 

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