Generally publishers are not liable to an individual consumer for advertising which results in a financial loss or damage to that consumer, however, third parties such as yourself can be held liable for disseminating certain advertisements if they helped to create the advertisement or knew or should have known that the claims made in an advertisement were false, deceptive or fraudulent.
Disclaimers, which are important to have, need to be prominently displayed and written in language that is clear enough for the average consumer to understand. A disclaimer no matter how clearly written, however, will not prevent a lawsuit nor will a disclaimer protect you from losing a lawsuit. The most a disclaimer can do is mitigate any damages awarded in a lawsuit, should you be found liable for the material you publish.
Therefore, it can be important for you to monitor the advertising on your site and avoid those ads that may mislead your readers.
There is a great source of information available to you through the Federal Trade Commission website. The FTC has not only guidelines for those who advertise and market their products and services on the internet, they also have a guide (designed for the media) on screening advertising.
See
http://business.ftc.gov and, in particular,
http://business.ftc.gov/documents/bus28-advertising-and-marketing-internet-rules-road and
http://business.ftc.gov/documents/bus36-screening-advertisements-guide-media (a pdf file).
I suggest you read through these publications for the advice and direction they offer.
Traditional news publications and broadcast networks have developed over the years advertising standards and guidelines that they follow when it comes to the advertising they will accept and the advertising they will reject for publication. While advertising revenue is vital to the health of most news organizations, reader loyalty and confidence is vital as well. There is also a responsibility of publishers to ensure that what they publish is honest and will not cause harm.
It would be wise for you to have your investment site, and your disclaimer, and the terms and conditions of using your site, reviewed by an attorney in your area. The attorney can let you know if there are any areas of legal concern that should be addressed.
Good luck with your investment site.