Who holds the copyright to a preprint article with multiple authors?

Question

Given a preprint article that is not submitted anywhere else, may be not even on a preprint server, who holds the copyright to the article?

To what extent do authorship contributions or being listed as an author affect the copyright status?

Answer 1

Copyright law varies, though there are common elements. Generally, assume that all authors hold the copyright jointly and equally unless other arrangements are made by the authors themselves.

From the University of California we get:

Co-authors own the work’s copyright jointly and equally, unless the authors make an agreement otherwise. Each joint author has the right to exercise any or all of the exclusive rights inherent in the joint work. Each author may:

Grant third parties permission to use the work on a nonexclusive basis without the consent of other joint authors

Transfer their entire ownership interest to another person without the other joint authors' consent

Update the work for their own purpose

A statement of contributions won't affect this, as long as all are authors.

The linked site has more information.