This is a logo owned by London Stock Exchange plc for Alternative Investment Market. It is a historical logo. Its historical usage is as follows: Launched 1995.
London Stock Exchange plc
The logo is from the <a rel="nofollow" class="external free" href="http://www.londonstockexchange.com/en-gb/products/companyservices/ourmarkets/aim_new/AIM">http://www.londonstockexchange.com/en-gb/products/companyservices/ourmarkets/aim_new/AIM</a> website. London Stock Exchange plc AIM Company Service webpage