Did the Queen signal a top in Twitter?

Did Queen Elizabeth II just signal the top of Twitter's growth?

The octogenarian great-grandmother sent out her very first tweet on Friday. Elizabeth Windsor already has nearly 800,000 followers, but this was the first time she tweeted herself.

It is a pleasure to open the Information Age exhibition today at the @ScienceMuseum and I hope people will enjoy visiting. Elizabeth R.

— BritishMonarchy (@BritishMonarchy)

But could the queen's joining of Twitter signalthe days of rapid growth for the social media giant are nearing an end? Shares of the company, which reports on Monday, are down 22 percent so far in 2014, in large part because that's what the market fears.

At the start of 2011, user growth on its flagship Twitter service was a brisk 25 percent or so. But by the second quarter of 2014, it only managed to add 6.3 percent to its user base.

(Read: Queen sends her first tweet, signed 'Elizabeth R')

The company still boasts 271 million active users and has a market cap of $30 billion. But that value may be too much, according to Chad Morganlander, portfolio manager at Stifel Nicolaus' Washington Crossing Advisors.

"It's a great company [and] great platform but our thought is that the valuation doesn't make sense," Morganlander said.

Though Morganlander expects Monday's earnings report to be good, he is worried the company's enterprise value-to-forward revenue ratio is too high. The company is expected to bring in $2.3 billion in 2015.

"This is a much more frothy company and it's just way overvalued,"he said. "Our price target or our entry point would be roughly about $30 a share."

Todd Gordon, founder of TradingAnalysis.com, also believes Twitter's stock could head down. He sees the stock as having held an uptrend since itslow on May 7. However, it is now trading down toward it recently-minted 200-day moving average. Both of these indicators converge at the $48 level.

(See: CNBC's Social Media coverage)

"There is some downside momentum in this space as well as the broader market," said Gordon, a CNBC contributor. "I'm wondering if that $48 level will give way and move down towards that lower $40 level in Twitter."

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