Lift and escalator manufacturers Kone, Schindler and ThyssenKrupp have been charged by the European Commission for allegedly running a cartel.
The Commission says the firms broke competition law
They are said to have done so from 1995 to 2004 in Belgium, the Netherlands, Germany and Luxembourg.
Commission investigators began their probe into the three firms last year.
If found guilty, Finland's Kone, Switzerland's Schindler and Germany's ThyssenKrupp could each be fined up to 10% of their annual turnovers.
Right of reply
Each now has two months in which to defend themselves in writing.
All three firms said they were looking at the allegations before making their replies.
"Now we start picking through their [the Commission's] statement and will reply in due time but I have no time schedule," said Kone spokeswoman Minna Mars.
Schindler is the world's number two lift-maker, and Kone is the fourth-largest lift and escalator company.
ThyssenKrupp's lift and escalator business operates in more than 100 countries.