... public relations firms are able to spin non-earnings announcements more than earnings releases. That’s very plausible, because earnings announcements contain precise numbers that can be seen through by analysts, making them difficult to spin, though not for want of trying.
... a trading strategy around earnings announcements: Buy companies that do not use IR firms and short companies that use IR firms. The logic is simple—since earnings expectations have already been bid up by the IR firms, stock prices of the companies that use them are likely to fall after earnings are declared, while the ones that don’t use IR firms will not see any such impact.
... suggest investors do not distinguish between media coverage arising from IR influence and media coverage from general newsworthiness, and are surprised when hard information turns out to be worse than expected. Investors, it appears, can be fooled, but not forever.