It doesn't matter how big or small your business is, as certain agreements are illegal regardless of your justification. More importantly, they're criminal. Here, size and position in the market matter. Interestingly, even small businesses can dominate a market if the product is unique and the market is small. In addition, mergers and acquiring ongoing business assets may require government authorization before the deal can close.
Some industries are more prone to antitrust challenges than others.
If any of these conditions apply, you'll want to be especially alert to antitrust concerns. The first line of defense is knowledgeable employees. It's wise to provide frequent training for all managers, especially those in sales, marketing, strategy, deal making and procurement. Pithy guidelines for recurring situations can also provide a handy way to remind those in your business what you expect. For example, guidelines on how to do benchmarking right and how to avoid potential anticompetitive pitfalls in trade association settings can be used repeatedly.