There are several tactics, ranging from mostly above-board kinda-scummy, but entirely legal, to absolutely illegal and beyond unconscionable. It depends on how far down you want to go with it.
I am a fan of making gradient lists for things of this nature. So, I will start with 1 being the most above-board method, and as numbers get higher they will get progressively scummier.
1. Cornering the market. This is the tactic of making yourself the only game in town in terms of selling a particular product. This can be done by several methods. The most common are 1. buying out all the suppliers of the component parts, and 2. selling the product at a loss for a period of time in order to drive out business from smaller competitors. After the competitors go under, you bring your prices back up to a more normal level. Both of these tactics only work with a large disproportionate wealth-gap between the person executing this tactic and their competition. Whole-sale buying out the competition is also an option.
(An example of this would be Youtube in the area of online streaming. They offered the Youtube partners program, which incentivized all the best creators to start using Youtube, because they were able to get payed as Youtube creators. They later started reducing the amount of money that Youtube partners earned, and then pushed it farther by demonetizing certain content. Youtube actually still, today, runs at a loss due to the partners program.)
2. Taking advantage of international free-trade in order to bring products in from countries with less ethical worker-rights laws, which enables the products to be sourced cheaper. (This, FYI, is why free trade is a mechanism of enabling evil to occur.)
3. Buying up politicians to implement laws on the industry that are cost-prohibitive to follow. This is another method of "cornering the market." Larger companies can afford to follow these strict regulations. Smaller competitors cannot.
4. Corporate spying. Discovering the secret methods used by the competitors in order to source or produce their products. If it's ONLY at the level of corporate spying, then this is followed up by copying their methods.
5. Minor corporate sabotage. This would be taking advantage of information gained via corporate spying in order to apply perfectly legal pressure against whatever method the competition is using. (This can also include tactics such as attempting to poach employees from the competition.)
6. Corporate smear jobs. Causing a scandal against the competition by accusing them of something (true or false) that the public would find morally repugnant.
7. Moderate corporate sabotage. This would be things like buying up a company that is a valuable source for another company's products, and then cancelling the contract. Or, otherwise driving their suppliers out of business via other methods on the list.
8. Plausibly-deniable corporate thuggary. Using plausible deniability to deal with gangs and crime syndicates to cause trouble for their competition's store-fronts and customers.
9. Executive targeted mafioso tactics. This would be the actual targeting of higher level executives and the family of executives with kidnapping and assassination.
Huh... how do my lists ALWAYS wind up being 9 items long? Every single time! I don't even do it consciously, it just always turns out that way somehow.
Anyway, as you move toward 9, it's not just that it becomes more morally reprehensible. It also exposes the person performing these tactics to more risk. As such, they would need reason to feel they can be rather bold before resorting to the higher numbered tactics on this list. On the other hands, the items closer to #1 don't actually work unless you are in a nation with very strict government order and rule of law. So, unless such a beaurocratic system exists, they are less likely to use those tactics. This means most cases usually trend toward the middle, with it only being the more extreme cases that go to either end.
