Twitter is said to be flying too high and too fast.
That's the opinion of Macquarie Research Equities, which downgraded Twitter stock Friday from "neutral" to "underperform," the firm said in a note.
"We continue to believe that Twitter as a company has a bright future and many opportunities ahead," analysts said. "However, as a stock, we believe nothing has changed over the last 15 days to justify the rise in valuation."
Twitter Inc.'s shares have nearly tripled since its initial public offering last month, including big gains in recent days. On Monday, for instance, Twitter stock gained while Twitter shot up almost 8% to $64.54.
Investors have been seizing on the momentum of the company's ad revenue.
Macquarie analysts, however, said the big gains in the last two weeks have been "too far, too fast" and come "on the back of virtually no news." Analysts still maintain their $46 price target for Twitter stock.
Shares for the San Francisco-based company on Friday were down 7.58%, or $5.56, to $67.75.