Assuming 30 trading days horizon, Atlantic Coal PLC is expected to under-perform the Iomart. In addition to that, Atlantic is 2.83 times more volatile than Iomart Group PLC. It trades about -0.07 of its total potential returns per unit of risk. Iomart Group PLC is currently generating about -0.19 per unit of volatility. If you would invest 13,700 in Iomart Group PLC on April 25, 2012 and sell it today you would lose (900) from holding Iomart Group PLC or give up 6.57% of portfolio value over 30 days.
Diversification
Average diversification
Overlapping area represents amount of risk that can be diversified away by holding Atlantic Coal PLC and Iomart Group PLC in the same portfolio (assuming nothing else is changed)