is there an statue of limitations for securities fraud?

There is almost always a clause in the purchase of securities which requires mandatory arbitration. I suggest you access the website of the Pope Law Firm, they are specialists in securities fraud and have a question and answer service.
The questioner might find some of my legal guides helpful:
My legal guides on law in general and about attorneys

• How to Select and Hire a Lawyer
• Understanding the Different Court Systems
• Limits on a Lawyer's License: What the Attorney Can and Cannot Do

• My commercial legal guides:
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• How to Lose Your Money in Six Easy Steps; How to Avoid being Scammed
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My legal guide on New York business law --
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LEGAL DISCLAIMER
Mr. Sarno is licensed to practice law in NJ and NY. His response here is not legal advice and does not create an attorney/ client relationship. The response is in the form of legal education and is intended to provide general information about the matter in question. Many times the questioner may leave out details which would make the reply unsuitable. Mr. Sarno strongly advises the questioner to confer with an attorney in their own state to acquire more information about this issue.

Of course, there are always statutes of limitations. But as an investor you need to concern yourself most importantly with your own claims in a civil action. Under the federal securities laws you have two years from the time you should have discovered the facts constituting the fraud, but not more than 5 years from the violation. If you bought stock pursuant to a fraudulent Registration Statement or Prospectus, you have only one year from the time you should have discovered the facts, but no more than 3 years.

You cannot file a criminal complaint. The government generally has 5 years to file a case for mail or wire fraud. If the scheme affects a financial institution the statute is ten years. But other statutes may apply, and the limitations may be tolled by an ongoing scheme.

I don't see how an agreed payment between the parties can affect your reposrting the violation, though you may be a whistleblower, or have some written agreement, both of which create other complications which must be addressed by a lawyer.

The above is not legal advice, nor is it complete. It is information based on a hypothetical situation about the law designed to help users safely cope with their own legal needs. But legal information is not the same as legal advice -- the application of law to an individual's specific circumstances. Although I go to great lengths to make sure this information is accurate and useful, I recommend you consult a lawyer if you want professional assurance that this information, and your interpretation of it, is appropriate to your particular situation.