If you get access to this kind of information before the investing public does, and either you or someone you know profits off of it, you will be guilty of insider trading.
Do you know what happened to Martha Stewart? She was given information about a company before the public got it (it wasn't M&A info, but the example still applies because it was insider trading), she traded stock based on it and she was busted. She spent time in prison for it, even though her criminal record was spotless until that point.
The only way you can get this information is to be an executive level employee at one of the companies, or be the accountant/attorney who is working the deal. But if you are one of these parties and you use the information to make trades, or give the information to someone else to make trades, you will get into serious trouble and maybe even have your professional license(s) revoked. Not worth it.