Newly minted M.B.A. graduates are stepping into a job market with the smallest share of companies planning to hire them in years.

Eighty-five percent of U.S. employers expect to hire M.B.A. grads this year, down from 91% in 2017, reflecting the biggest drop in business-school recruiting since the start of the recession, according to a survey by the Graduate Management Admission Council, a nonprofit that administers the GMAT admissions exam.

The...