The latest number, bruited about, as reported elsewhere on this site by people like Tyler Durden, is 60 billion. That's up from 25 billion.
A reasonably acceptable estimate of Citigroup's overal earnings power is something like $20 billion. (Our guess is that it might be too high, rather than too low, but that's a minor quibble.) That would be worth quite a lot if there were only 4-5 billlion shares outstanding as was the case about eighteen months ago.
Not so much with 25 billion shares: 20/25=.0.80 a share (let's just cancel out the billions from both numerator and denominator). With 60 billion shares, that's more like 0.33 a share. Hmmm, at ten times earnings the stock should be worth about $3.33. No great bargain here at today's prices.
Book value tells a similar story. If it were $100 billion with 4-5 billion shares, that would be $20-$25 a share. At say, $250 billion with 60 billion s... that's a little over $4.00 a share.
In the end, it's not how large the "pie," is but how many ways the "pie" is going to be divided that counts. Any current or (recently) fromer GM holder can tell you that, because they watched their shares go from double digits, to single digits, to "penny stock," probably on its way to 0.
Disclosure: In and out (but currently out) of C.