With 100TH (now 200TH) bitcoin mine you get 400MH/s for every share and that is it.
You buy 1 share of 100TH mine for 0.2BTC.
In 1 month your 1 share have produced 0.05BTC.
But price of share has dropped to 0.1BTC.
Another months passes your earned additional 0.03 for total 0.08BTC, but
share price has dropped to 0.05BTC and is now worth 0.05BTC.
Total earned 0.08BTC with share price at 0.05.
Or 0.2BTC invested 0.13 returned.