The amendments make clear makes clear that, where a company makes a "strategic review announcement" which starts an offer period, any potential offeror with which the company is already in talks with regard to a possible offer will be required to be identified in the announcement.
In such cases, the announcement must also specify the date on which the "put up or shut up" deadline will expire.
In addition, the amended Practice Statement encourages companies and their advisers to consult not only before making a strategic review announcement but also before making any statement that confirms that the strategic review is continuing.
A 28-day period from bidders being identified and the requirement to withdraw or make a bid brings into focus much deeper due diligence in a shorter timeframe than may have previously been the case.
Peter Baynham, UK head of M&A consulting at Mercer, said: "Bidding companies initially tend to focus on the financial and legal aspects of a deal - considering the impact on employees much later in the process. The new rules will concentrate companies' minds on having early plans for organisational integration and restructuring effects, so they can move quickly if there is a leak.
"Many deals fail to deliver value to acquisitive companies due to lack of timely planning and communication around people and integration, which may lead to poor morale, reduced productivity and leakage of top talent." Mercer has also highlighted the increased role that HR directors will need to play in evolving an early people strategy for prospective acquisitions.
"In the past, HR directors have tended to receive a late invitation to the deal table. The rule changes should prompt a higher profile for HR in the early development of business expansion strategies," Baynham added.