IMO, releasing the PR mid-day could cause a halt in trading, as per regulations:
"When a company is listed on a U.S. stock exchange, including NYSE, NYSE MKT, NYSE Arca, the NASDAQ Stock Market and the BATS Exchange, it agrees to notify the listing exchange about any corporate developments that could affect trading activity in its stock—before announcing them to the public. These developments can include:
changes related to the financial health of the company;
major corporate transactions like restructurings or mergers;
significant positive or negative information about its products;
changes in key management individuals; and
legal or regulatory developments that affect the company’s ability to conduct business.
For their part, the listing U.S. stock exchanges have the authority to halt trading based on their evaluation of a given announcement. Generally, the more likely the announcement is to affect the stock price, whether positively or negatively, the more likely the exchange is to call for a trading halt pending dissemination of news by the issuer. "
We won't know until we know, but it could happen, IMO.