Financial improvements

[mp4]

When a city "builds" Capitalization the amount of money collected can be improved by Marketplace, Bank etc.

Does anyone know by which factor the amount of money is increased in a city which have all three financial improvements?
Is it worth the effort to build a Stock Exchange? If I don't build any of these improvements I get a lot of money during the time it takes building them. Does anyone know which time it takes before the city with a Stock Exchange has generated more money than the city without?

[La Fayette]

Here is the way it works:
You need either trade or specialists (taxmen).
Trade is provided either by trade arrows collected within the city radius (for example 2 arrows if you work an ocean square in the early game), or trade routes (max = 3/city).
Trade is then divided into taxes, luxuries and science (beakers).

1) Without improvements:
Let us suppose that your city produces 10 trade arrows, has one trade route value 2, no corruption, and settings at 50% taxes. This gives you (10 + 2)*50% = 6 gold.
A taxman provides 3 trade arrows. Then 2 taxmen provide you 3*2 = 6 gold.
6 + 6 = 12 gold. This is what you get each turn in my example, with no improvement in the city.

2) With improvements:
Each improvement (MP, Bank or SE) provides 50% surplus (which means 6 gold in my example), BUT it also has a cost.
Therefore, my city with a MP inside produces 12 gold + 6 gold - 1 gold = 17 gold.
With MP and Bank, it produces 17 gold + 6 gold - 3 gold = 20 gold.
With MP, Bank and SE, it produces 20 gold + 6 gold - 4 gold = 22 gold.

3) Conclusion:
Let us look at the Bank in my example: it provides you 3 gold/turn.
OK, but building a bank costs about 240 gold. This means that you need 240/3 = 80 turns to pay back your investment! (if the city doesn't grow).
This is a very low return.
This is the reason why good players very seldom build Banks or SE, only in very big cities.

[shade]

BUT MP,Banks,SE also give luxuries this gives a second reason to build them.Happy ppl don't ask(=really need it to stay out of disorder) for a temple or colloseum.

Also if you have a bigg city with a lot of trade the influence of Superhighways can be enormous since they add 50% trade arrows pumping up science,happines and GOLD

Shade

[The Mad Monk]

BUT MP,Banks,SE also give luxuries this gives a second reason to build them.Happy ppl don't ask(=really need it to stay out of disorder) for a temple or colloseum.

That, along with the potential for perpetual WLTXDs (on 20-30% luxeries) is why I always build all of them in all my cities, as soon as is practical.