Which of these two is correct?
Most company is private
Most companies are private
In general, should most be used with a singular or plural noun? And will the verb "be" be plural or singular?
This question is too basic; it can be definitively and permanently answered by a single link to a standard internet reference source designed specifically to find that type of information. See the Help Center for guidance on how to improve it.
Most is what is called a determiner. A determiner is "a word, such as a number, article, personal pronoun, that determines (limits) the meaning of a noun phrase." Some determiners can only be used with either a countable noun or an uncountable noun, while others, like most, can be used with both countable and uncountable nouns. Uncountable nouns usually take a singular verb.
So, in your example, this is the correct form for your sentence: "Most companies are private." The plural noun is needed after the word most (company, referring to a business entity, is a countable noun, with a standard plural form [companies]), and then the plural verb is needed to construct a grammatically correct sentence.
But a sentence such as, "Most information is now obtained from the Internet." would take the singular verb (since information is considered an uncountable noun).
Interestingly, company can be an uncountable noun, but it then has a different definition than in your example. For example, " Most company leaves after two or three days," is a perfectly acceptable sentence. In this case, company has the definition of a social gathering of guests or companions.
Think of most as the majority of. Surely you would say the majority of comanies are... - wouldn't you?
Furthermore, of the is required if you limit the sample in any way. A. Most men are stupid. B. Most of the men in that club are stupid. C. Most of the men in the world are stupid.
Sentences A and C seem the same in principle, but only A is completely unlimited. The same applies to uncountable nouns. D. I've put most of the sand in that barrel.