The Biblical Parable of Talents, present in Matthew 25:14-30 and Luke 19:11-27, Jesus tells a story of a rich master who put three servants in charge of varying amounts of wealth while he was away.
Two servants invested the talents they had been given, and increased their master's wealth during the time he was away. They were both rewarded for their efforts. The third servant chose to bury his talent, returning to his master the same amount he was given. The master admonished the servant, saying,
"You wicked, lazy servant! So you knew that I harvest where I have not sown and gather where I have not scattered seed? 27 Well then, you should have put my money on deposit with the bankers, so that when I returned I would have received it back with interest.".
While the parable does not describe actual events, it would have to describe an actual financial system for the listener to understand it. I have been wondering how that system worked. Did First Century bankers invest in the same way that we understand investing today? Did they purchase trade goods to sell at a profit and then share said profit among investors? How did they determine the proper amount of interest a depositor should receive?
This is a pretty specific question, so thank you to anyone who takes a crack at it!
I looked at Derrett, Law in the New Testament, which is a key secondary source for this kind of thing. He talks about this parable from p17 onwards, but he is mainly interested in discussing the question of investment, returns, etc.. He does discuss the banking, but only briefly on p26. There are a few secondary references there to follow up as well.
Basically, banking was a fairly low-profit endeavour marked by (a) placing a deposit of money somewhere secure. So security was the key factor. (b) money-changing between currencies. Compared to investment, ‘banking rates’ were quite low, which is one of the reasons why the first two servants invest the capital – 1000 an 500% returns were not unheard of or implausible for capital investment. Banks generally did not loan speculatively – i.e. they didn’t loan deposits out in order to gain profit. However banks did serve a as a means for a system of credit and debit, including inter-provincial transfer of ‘money’. In this regard, Roman banking was quite sophisticated. There’s an article on this by Peter Temin, ‘Financial Intermediation in the Early Roman Empire’
For more reading generally about banking in the Roman context, there’s a PhD thesis by C.T. Barlow, ‘Bankers, moneylenders, and interest rates in the Roman Republic’.
I know that doesn't fully answer your question, but I think it's a start.
Banking and investing in the Greco-Roman world generally took place in the context of temples. Temples were even responsible for minting money and for stockpiling money to be used for key events/celebrations. Investing probably was about changing currencies for people, it may also have been about buying and selling animals to be used for ritual sacrifices, which is what the money handlers at the temple were probably doing when Jesus tried to clear them out. So someone who was travelling to the Jerusalem temple in order to make a sacrifice wouldn't travel with whatever animals he was going to sacrifice, he'd likely travel with money and then purchase the animals outside the temple.