Good display ad network / affiliate / advertising program to monetize finance/trading game

Hi fellow Indiehackers,

I've been active here for a some time as a reader and podcast listener.

I've now stumbled into a bit of success for the first time by launching a stock trading game so I created an IH account. Daily stats since a few days:

• roughly 400 unique users / day
• 500 sessions / day
• 6K pageviews / day

No way I can monetize by asking users to pay, so I was thinking about ads (some basic quality would be preferred). Adsense doesn't work (not a content page).

I have no clue about ad networks. I've googled a lot, but it's really hard to judge from the website. Does anyone of you have any experience/recommendation for an ad network, maybe specifically for finance-related ads?

Thanks!!