The Brit will be looking to break Michael Schumacher’s record of seven world titles this year after equalling that total last term.
But it has been a jumbled start to the campaign after months of speculation over his future as contract talks between him and Mercedes rankled on.
Eventually, Hamilton penned a one-year deal with the Silver Arrows but the latest news will come as a further blow.
He took care of his business interests and logistics as the driver’s brand continued to grow, particularly over the last seven years.
Hynes was also in charge of Hamilton’s ‘Project 44’ management company after Simon Fuller was dismissed.
But according to the Daily Mail, the 43-year-old has now split from the two-time Sports Personality of the Year winner.
With the season set to start on the 28 March, Hamilton is now in a rush to replace his close pal with time running out.
A source told the Daily Mail: “Marc and Lewis have known each other since they were young, as friends first and business partners second, so, while they are parting ways in a business sense, they remain close friends.”
Hamilton will get into Mercedes’ W12 for the first time in Bahrain on March 12, when pre-season testing begins.