Yes. As a matter of fact, the normal procurement/business process with these companies is to sign a mutual NDA, that covers disclosing business information for both parties, and doesn't allow that to be disclosed to third parties without written approval. This is incredibly common in the electronics industry.

By the way, the company that I work for has such corporate NDA's with at least five of the companies you mentioned. I doubt even one laughed when signing the corporate NDA was discussed. As it is mutual, it protects them, as much as it does us. In my career I've worked for two IC manufacturers, two Computer/Laptop manufacturers, and a more general consumer electronics company, as well as a co-owner of a startup in the consumer electronics area. Signing NDA's at the start of a business relationship was never a big deal... It was expected.

I agree that if Fortress told the other installer that they received a quote request for the job, they are sleazy. I said that in my posting earlier in this thread. But you can't count on companies/people having ethics, you need to protect yourself, and an NDA does exactly that. It puts both parties in a position of being able to expect a behavior, and being able to collect damages if the agreed upon behaviour is breached.