M&A (mergers and acquisitions) isn’t exclusively one or the other. It’s an umbrella term covering both sides of a deal.
Sell side refers to advisors representing a company that’s being sold or seeking a merger. Their job is to find buyers, negotiate favorable terms, and maximize value for the seller.
Buy side refers to advisors representing the company or investor looking to acquire a target. Their job is to identify opportunities, conduct due diligence, and negotiate favorable purchase terms.
Investment banks and advisory firms often have dedicated M&A teams that work both sides, sometimes on different deals simultaneously (with appropriate conflict walls). So when someone says they work “in M&A,” they could be doing sell side, buy side, or both, depending on the firm and specific role.