Shares of Zuora Inc. have plunged 7% in Thursday morning trading, giving back some of their gains from the past week. The stock had been on a six-day winning streak, gaining 46% in that time following the company's strong earnings report and its customer conference. Zuora makes tools that help companies adopt subscription business models. On Thursday, Morgan Stanley analyst Stan Zlotsky pumped the brakes on the Zuora enthusiasm, writing that while there were some encouraging signs at the conference, which wrapped up Wednesday, there are also some reasons for caution. "We didn't pick up meaningful interest or adoption of newer add-on products such as Zuora CPQ and Zuora Insights," Zlotsky wrote. "Among the reasons for limited adoption was stronger competitive alternatives like Salesforce.com's CPQ solution." He raised his price target to $24 from $22 but kept his equal weight rating intact. Shares have gained 45% in the past month, while the S&P 500 has risen 3.8%.