The forums are a venue for the issuance of loans but a select few participate given the risks involved (theft). There is no banking system (tried, failed though some trying to start) and there is no easy way to issue shares or bonds.
The main issue is trust - i.e. the likelihood that the borrower just walks off with the ISK and refuses to repay is quite high in Eve (Jita local chat is a case in point). There are trusted third parties that can act as an escrow but they are limited.
However, if players or corporations could issue shares or bonds (i.e. borrow from others) and there was some enforcement mechanics behind it, much like the current contract system or market escrow system, then i suspect this would lead to a major ISK sink , but an enjoyable one. It could also lead to the start of a financial system in Eve Online in which the mass player base could participate in.
More in the Sink below (i suspect it would come from lost ventures) but first the mechanics.
Or - how to enhance the current contract system to make loans work mechanically:
Lets say i was willing to lend someone 1bn ISK at 10% interest for 3 months, secured on 1.3bn ISK of items as collateral. The trick is to ensure i can't just run off with the 1.3bn of items if the borrower is able to pay me the loan + interest within 3 months.
I would need an item exchange contract (we can do that) combined with a time based item exchange contract (we can't do that right now), and issued at the same time as part of a combined contract (i.e. the borrower and lender must enter into both contracts at the same time to make this work - we can't do that either).
Step 1 - The item exchange contract would see me pay the borrower 1bn ISK and the borrower give me 1.3bn of Items (specified by me). We can do that today with the current contract system.
Step 2 - The time based item exchange contact (set up at the same time) would be for the borrower to pay me 1.1bn within 3 months (i.e. the 1bn ISK + 10%) in exchange for those same 1.3bn of items.
Hence, on day 1 the borrower receives 1bn of ISK and 1.3bn of items are effectively put into escrow and only come to me after 3 months if the other player has not repaid me 1.1bn ISK.
Assuming my thinking is correct - the mechanics should hold. It is in the borrowers interest to pay me the 1.1bn ISK and i can't touch the 1.3bn ISK of items until 3 months is up and the borrower has not repaid me.
And this is where it would get interesting. There would now be a clear financial incentive for the borrower to repay the ISK + interest and the lender would be well protected (essentially via an over collateralized loan).
Therefore, unless the lender does not mess up with their collateral requirements they will not lose ISK.
The borrower, if unable to pay, would though lose their items and they would be sold by the lender to (hopefully) buy orders in the market. Using the above example essentially 1.3bn ISK of items are now longer available to the borrower to use as new collateral to get new loans + 1.3bn of buy orders have gone and so presumably those prices have fallen + therefore there is not a requirement to manufacture those 1.3bn of items. In all, the Eve economy has shrunk due to this borrower defaulting which leads to an effective ISK sink . . . . . though admittedly in the beginning it will really be items not in use being re-circulated into the Eve market - but this would allow corporations to put those dead assets in play to allow them to borrow funds to wage war!
Worth noting, that the appearance of this mechanic in the game would create much more than just the ability to issue loans. It would also allow the appearance of forward trades (i.e. derivatives).
Lets say that you wanted to buy 1bn of Tritanium at todays prices, paying in 1 months time for your manufacturing schedule but you feared the price was going to go up by 10%. And lets say that I took the view that the price of Tritanium was going to be flat or be lower in 1 months time.
Hence, as we stand today i would be happy to deliver to you the Tritanium in a months time for 1bn ISK at todays prices. . . . . i believe i would make a profit and you would feel you saved from buying at a higher price.
And lets also say that you were willing to pay 20m ISK now to guarantee paying that price for the Tritanium (i.e. you pay 2% of the buy price = 1.02bn ISK in total).
Using the above mechanics:
Step 1 - the first item exchange contact would be for you to pay me 20m ISK and for me to exchange 300m ISK of items.
Step 2 - the second time based contract (but issued at the same time) would be in a months time you paying me 1bn ISK (so 1.02bn ISK in total) and the 300m ISK of items returned for me exchanging with you the 1bn worth of Tritanium at day 1 prices.
(If i break the second time based contract you get 300m ISK of items for 20m ISK which will cover the rise in the price of the Titanium.)
So, if the price has indeed gone up by say 15% you will have saved 13% (15% price rise less the 2% cost of this contract). If the price has fallen by 5% then i will have gained 7% (5% less cost to buy the tritanium + the 2% fee paid to me).
Of course, if the price is more than 30% higher then i will not pay the second part of the contract and so lose the 300m ISK of items and we both lose but you are least are 280m (300 - 20) better off.