Wall Street's "early bird catches the worm" game faces the biggest challenge in history as top investment banks collectively counterattack.

Last summer, during the training course that kicked off the highly competitive junior analyst program, J.P. Morgan executives noticed unusually low attendance rates, sparking their curiosity and concern. They discovered the reason: new employees were skipping the mandatory onboarding training to interview for a second job at a private equity firm, even though their first job had just begun a few days ago. This practice, known as "pre-hiring," is when private equity firms recruit investment banking analysts in advance, with the positions typically starting one to two years later. As their recruitment efforts begin earlier and earlier, this has angered banks that invest millions in training junior staff, as once the program ends, they are being poached by private equity firms. Goldman Sachs has become the latest bank attempting to prevent analysts from "pre-hiring," as the company plans to require new hires to prove every three months that they have not accepted a job offer from another company. Last month, J.P. Morgan threatened to terminate candidates who accepted future job invitations.