Twitter's sliding share price and plateauing new users coupled with the fact that CEO, Dick Costello, stepped down last week, has caused concern among investors and existing users alike.

In an interview with Forbes in America, Managing Director of Magid Associates, Tero Kuittinen, said that Twitter was not only not in the top ten apps in the US but not even in the top 20.

"Twitter is not even a top-20 application in America anymore. It’s really struggling to maintain momentum. At the same time you have this cluster of really young vibrant apps like Snapchat and Kik and even Dubsmash, that are racking up massive download numbers," Kuittinen said.

Last week saw Twitter CEO Dick Costolo step down to be replaced by co-founder and chairman, Jack Dorsey, who's filling in on an interim basis. The move is widely believed to be a consequence of significant challenges facing the social media giant.

Twitter's growth in users has slowed to 18 percent in the first quarter of 2015, a reduction of 2 percent from the final quarter of last year.

Twitter's launch of live-streaming app, Periscope, is a move in the right direction given the emphasis being put on video in social media. However, it may take a significant change to help Twitter re-secure its place as the second-biggest social media site.

Dick Costolo's replacement as CEO of the company still remains up in the air and the possibility of hiring from outside is quite strong.