Still, it's important to note that the company is still growing and hasn't posted declining growth. Amongst the seven largest Airbnb markets – namely the US, France, Italy, Japan, Spain, U.K. and Germany – available listing nights still grew at 40 percent year-on-year over the last three months, UBS said.

Airbnb was not available for comment when contacted by CNBC.

UBS found that worldwide year-on-year growth of Airbnb available listings per month has been on a downward trend since October 2016. For example, Airbnb available listings in that month grew around 110 percent, while in February 2017, it had slowed to around 35 percent.

The Swiss investment bank analyzed data from 127 cities where Airbnb is present to look at growth of the company's listings and impact on hotel brands.

Airbnb's growth rates have slowed in the past few months partly due to increased regulation around the shared accommodation sector, UBS said in a note released on Wednesday.

Airbnb's listing nights booked hit 52 million in 2016 versus 25 million in 2015, more than doubling, UBS said. Gross bookings worldwide have also more than doubled and reached $6.4 billion in 2016.

Many cities around the world have moved to regulate shared accommodation, which is a reason behind the recent slowdown in Airbnb's growth. For example, in Barcelona, a special license is required for short-term rentals. The city stopped issuing licenses in 2014, so the only way to start a new Airbnb would be to buy an existing property with a license, UBS said. Airbnb was fined 600,000 euros ($638,454) by the Barcelona city council for offering unlicensed accommodation on its site.

New York meanwhile introduced legislation allowing the state to fine Airbnb hosts for listing properties for terms less than 30 days if a permanent resident will not be present.

"Our analysis suggests it is likely that regulation is having a negative impact on the supply and demand growth of Airbnb, especially in New York and Barcelona. Both cities showed year-on-year declines in available listing nights of around 10 percent in Feb 2017," UBS said in its note.

But this is not necessarily the case for all markets where regulation has been introduced.

"We believe that the findings are less conclusive for San Francisco, London and Paris, although in our view it appears there is a negative impact from regulation on Airbnb listing night growth given the slowdown," UBS said.

The negative impact of regulation does not remove Airbnb as a threat to hotel chains, but it does reduce it, UBS concluded.

"Nevertheless, we believe Airbnb is still likely a threat to hotels, but think the change in regulations has reduced the magnitude of the threat," the investment bank said.