请教Handbook: [Standard I: Professionalism] Buy-side Client 的问题 research, reporting, corporate, 的

水墨青花

请问,"Standards of Practice Handbook" page 23 [Standard I : Professionalism]讲Buy-Side Clients中有一段话我不是很明白：

Portfolio managers have a responsibility to respect and foster the intellectual honesty of sell-side research. Therefore, it is improper for potfolio managers to threaten or engage in retaliatory practices, such as reporting sell-side analysts to the covered company in order to instigate negative corporate reactions. Although most portolio managers do not engage in such practices, the perception by the research analyst that a reprisal is possible may cause concern and make it difficult for the analyst to maintain independence and objectivity.

请问，这当中的portfolio manager是buy-side对吗？为什么portfolio manager有可能threaten or engage in retaliatory practices, 这对portfolio manager有什么好处吗？还有就是，为何“reporting sell-side analysts to the covered company"会造成"instigate negative corporate reactions"？ 最后一句中说的independence and objectivity，针对的是sell-side analysts 的客观独立判断力吗？