If Marriott and Best Foods work together to increase both profits, that's not an anti-trust violation just because they work together. The article you cite enumerates a number of categories of violations, but you haven't identified which one you think "working together" inherently violates. My guess is you are talking about Monopolization, but since neither Facebook nor Apple is a monopoly, and since Facebook and Apple do not compete against each other, I'm not sure how that fits.