William Blair analyst Ralph Schackart downgraded Stitch Fix to Market Perform from Outperform following last night's fiscal Q1 results. The analyst says that despite his enthusiasm for Stitch Fix's "innovative model," for the second sequential quarter, the company missed on its key active clients metric. Last quarter, sequential net adds of roughly 54,000 came in less than the Street estimate of 128,000, Schackart tells investors in a post-earnings research note. Further, management guided to flat sequential active client growth in fiscal Q2, compared with the Street's expectation of an increase of 118,000 and despite the introduction of a new Kids category in the fiscal first quarter, adds the analyst. He cites a lack of visibility "into this key metric" and greater risk to out-year sales and earnings estimates for his downgrade of the stock.