I would love for someone to tell me I'm wrong so I can just give up on AM and hold BTC for the long haul.
Disclaimer: I own AM shares.
The current block number is ~341,660 and the next halving takes place at block 480,000 (sometime in late summer / early fall 2016). So there are ~138,000 blocks to go or about 3,500,000 bitcoins left.
In order to have 0.25 btc / share, AM with 400,000 share would need to mine 100,000 after hardware costs, electricity, maintenance, salary, rent, etc. These costs are highly variable. Lets say they are making 25% 'profit' (only AM knows this number, this may be way too high, but let's go with it for this calculation). This means that AM needs to mine 400,000 bitcoins out of the next 3,500,000. Put it another way, AM needs to have ~11% of network hashrate until the next halving (18 months or so).
This is just a quick calculation based on some highly variable numbers. Is this possible? I have no idea. I just did a quick calculation based on your post.
Would that calculation not be for AM to pay out .25 btc a share?
That is entirely different to being worth IMO, you have future worth to factor in.
If stocks can pay out even 25% interest they will probably shoot up in price, and be considered a great investment.