Kudos for being transparent about the problems with your exchange. I know that some people doubted you at first when the XCP was stolen, but that turned out to not be your fault. Now when it actually
is the fault of your exchange you are immediately holding your hand up. That takes courage and shows your integrity!
I agree with all the previous posters here who have suggested that you sell some shares of your exchange instead of dramatically raising the fees across the board.
I know that a lot of people don't like
https://cryptostocks.com/ but I think that has more to do with the projects/companies that are listed there than the actual exchange itself. It would be an easy and quick way to raise the money needed to re-pay what was stolen, and your users wouldn't be forced to take a loss.
Raising the fees to 1,5% is only going to hurt the exchange IMO, even if it's temporary. Perhaps you could increase them 50% from the current level, but increasing them to 1,5% is really a lot!
I have another suggestion.
It's kind of depending on if you follow through with the idea of doing an IPO or not, but I think it's something worth considering if you do.
How about raising enough money to
create an "insurance fund" that will be available for those users who are willing to accept a slightly higher trading fee than
uninsured users?
You would keep this fund in cold storage and it would be completely transparent on the blockchain for everyone to verify. It would only be used to reimburse those accounts that had paid the higher trading fee in case of another hack of the exchange. By making it
voluntary it doesn't hurt anyone who doesn't want to pay the extra fee, and as the income from the insurance premiums increase so will the level of insurance. This will make Poloniex the first exchange where user funds are insured. Perhaps you could even make the funds on that cold storage account multisignature with 2 trusted members from the community, that way anyone who doubts your integrity will feel a lot safer as well...
I know that I would certainly be willing to pay a slightly higher fee to sleep a little better knowing that even if you are hacked again at least I will get reimbursed, and I'm sure there are a lot of sad MtGox users who feel the same way.
I'm embarrassed to admit that the second I saw something about Poloniex being hacked I immediately attempted a withdrawal of my BTC from there.
They are now "stuck in limbo" but I assume that they will show back up again once you have reversed the attempted transactions?