GRAPHIC-Now 21, Britain's AIM is still struggling to grow up

* AIM vs the rest: http://bit.ly/28JoEmv

By Atul Prakash

LONDON, June 20 (Reuters) - With (Other OTC: WWTH - news) a few exceptions, London's Alternative Investment Market (AIM) is the only segment of the UK stock market that has, on average, lost money over the past two decades.

Britain's junior stock exchange opened 21 years ago to give investors a way to buy into smaller, unproven companies that promised fast growth, but it has consistently lagged the broader market in share price performance.

The main AIM benchmark has fallen 30 percent from January 1996 until now. By comparison, UK mid-caps surged 317 percent and small caps gained 130 percent. Chart: http://bit.ly/28JoEmv

AIM opened in 1995 with 10 companies valued at a total of 82 million pounds ($120.47 million). Now (NYSE: DNOW - news) , it includes around 800 firms, including British online fashion retailers ASOS and Boohoo and Majestic Wine (LSE: WINE.L - news) , whose market caps range from 310 million to 2.9 billion pounds.

ASOS (LSE: ASC.L - news) and Majestic Wine are among the few exceptions returns. They underscore the high-risk, high-reward nature of AIM. ASOS shares have surged 15,000 percent since its listing in 2001, while Majestic Wine is up around 800 percent.

Prospecting for the next ASOS is getting harder as poor returns, volatile markets and jittery investors have taken a toll on new listings.

The number of new AIM listings peaked at 519 in 2005. Last year, the number fell to 61. Through May of this year, AIM has seen only 34 new listings, according to LSE data. ($1 = 0.6807 pounds)

(Editing by Vikram Subhedar, Larry King)