I signed an offer letter but later realized that an annual performance bonus is not issued by the company nor is profit sharing. Companies that I have worked in the past provide a performance bonus at the end of the year which was 10% of your base salary. Can I request that my base salary be increased to accommodate for the lack of a company performance bounus? I signed the offer letter 10-28-14 and scheduled to start work 11-11-14
You can ask for anything.
However, the time has passed for negotiation when you signed the offer. An offer was made and accepted and to come in after the fact would likely cause very negative feelings toward you.
Should you ask? In my opinion, absolutely not. It will send the message that you are either unreliable or that you don't pay attention to details.