Was signet the publishing company for Stephen King 1981?

You're close, but not quite right! Signet is the publishing imprint of New American Library (NAL), which was owned by Penguin Random House.

Stephen King's early books were published by Doubleday.

However, Signet did publish several of King's books in paperback format. This was common practice at the time, where publishers would license paperback rights to another company.

To give a specific example:

* "Cujo" was originally published by Doubleday in 1981.

* Signet then published the paperback edition of "Cujo" in 1982.

So, while Signet wasn't Stephen King's original publisher, they did play a significant role in making his books accessible to a wider audience through their paperback editions.