May 3 (Reuters) - Cathie Wood"s Ark Investment Management bought about 1.3 million shares of Twitter Inc worth $71 million last week after the stock fell on disappointing results, Bloomberg News reported here on Monday, citing an email on the firm"s trading activity. Ark Investment Management did not immediately reply to a request for comment, while the microblogging site declined to respond. Twitter’s shares closed more than 15% lower on Friday after the company offered tepid revenue guidance for the second quarter, warned of rising costs and expenses and said user growth could slow as the boost seen during the COVID-19 pandemic fizzles. Reporting by Akanksha Rana; Editing by Shinjini Ganguli Our Standards: The Thomson Reuters Trust Principles.