Sot the rules in 5.3 must be
Stock of Corporations that have not yet operated may not be sold from the Pool.
That should be "to the Pool" not "from the Pool." The actual rule is "Stock of Corporations that have not yet operated may not be sold." The implicit addenda is "may not be sold [by players]" -- players are always allowed to purchase shares in companies, thus the bank and the pool may always 'sell' shares.
Without that, if a company have not yet operate, how could the players buy shares, the President Certificate and operate?
Shares that have never been owned by players are purchased from the bank.
In other forum I received this answer:
When a player buys a share, hehttp://www.boardgamegeek.com/thread/127845
- takes it from the bank (new share) or the pool (share sold by another player)
- pays the money into the bank: original price (new share) or current market value (used share)
In 18FL, shares are always purchased at current market value, whether purchased from the bank or the pool. The original price is not tracked as it is in many other 18xx games.