LONDON: The European Union needs to study the rise of special purpose acquisition companies (SPACs) but it is too early to say if they are a "bubble", the executive director designate for EU securities watchdog ESMA said on Thursday.

Dubbed "blank check" companies in the United States, SPACs have attracted billions of dollars in investment on Wall Street and their popularity has spilled over into Europe.

"They beg the question for us in Europe, what that means and whether we are comfortable with our existing rules," Natasha Cazenave told the European Parliament.