The most pirated acts are likely to be the most popular, finds the study
File-sharing sites help make popular acts more popular, finds a study.
The research, by industry body PRS for Music, showed the most pirated pop songs tend to be those at the top of the music charts.
There was little evidence that file-sharing sites helped unsigned and new bands find an audience, it found.
It suggests file-sharing sites are becoming an alternative broadcast network comparable to radio stations as a way of hearing music.
The study, carried out by Will Page, chief economist at the PRS, and Eric Garland, head of media tracking firm Big Champagne, looked at patterns of music usage among file-sharers.
It aimed to see if that pattern of use had any lessons for the way music is marketed and sold.
Many have claimed that the unprecedented amount of choice on the web would give rise to new models of music distribution.
This "Long Tail" argument, say the authors, claims: "If you offer people more choice, and help them make that choice, they will take that choice."
Action against pirate sites has not stopped swappers, said the study.
If true, this could mean that music makers should focus attention away from a few popular acts towards the mass of bands with smaller, dedicated followings.
However, found the pair, usage on file-sharing sites closely mirrors that on legitimate music sites. There was no evidence of the Long Tail operating.
The authors wrote: "Much of the volume (sales or swaps) is concentrated amongst a small proportion of the available tracks."
The reason for this, claim the authors, is that there is too much choice on file-sharing sites.
The breadth of music available means that people do not have time or do not want to search through it all or listen to it all for the tracks that they might like.
Instead their searches are constrained by what they see in the media, and what their friends are listening to.
They said: "After taking into account some geographic differences, the top of the many music charts, from licensed and unlicensed venues, are markedly similar."
They added that BigChampagne had never seen a big hit on the pirate networks that was not also a top seller in the licensed world.
Mr Page and Mr Garland suggest that file-sharing sites are reinforcing divisions in the music world and only making the popular more popular.
Despite this, the report said, the fact that music was free on file-sharing networks meant people did occasionally listen to bands they had never heard of before.
By contrast, on sites where people have to pay to listen they only download the tracks they know they want.
"If the sellers sell it, it might never be bought; but if the swappers offer it, at least one person will likely take it," said the study.
Given this, said the authors, it might be worth music companies regarding file-sharing sites as comparable to radio and TV as a broadcast network.