Why sign news releases?
Digitally signing of your news releases helps protect their integrity and avoid appearence of fake news seemingly issued by your company.
Consider the following situation. You are a publicly traded company. You often publish important business documents such as quarterly reports, profit expectations, press releases etc. These documents first appear on the web (your site and many news sites) and influence the price of your shares on the stock market. Assume that someone published false news (e.g. stating losses while you had profits in fact) by either breaking into your site or submitting a false document under your name to news sites. Or an error was introduced by news editors when preparing your press release for publication. Before the error or hoax is discovered, many people will read the document and act accordingly. This can be used to manipulate stock prices and harm your business reputation.
Solution. Sign your reports, reviews, press releases when you publish them on the web. This is the only way to ensure document integrity. If an electronically signed document is edited (by error or by evil will), signature verification will fail, it will be immediately evident to everybody. If you always sign all your documents and an unsigned one appears one day on the web, it will be evident that the document is untrustworthy. The harm is reduced and any errors or hoaxes discovered faster.
Read these stories about past web hoaxes reported in the press.
Emulex Web Hoax Not the First . . . and It Certainly Won't Be the LastFBI arrests man in shares hoax
Internet hoaxers target Lucent
Man Gets Probation and Home Detention in Online Stock Hoax
Don't Believe What You Read
Even SEC (Securities and Exchange Commission) reacted to web hoaxes by issuing a fake news release from a nonexistent company: Fake site set up to warn investors