Tech Mahindra, India's fifth-largest software company, reported fourth-quarter revenue below analysts' estimates on Thursday and unveiled a three-year turnaround plan.Consolidated revenue fell 6.2% year-on-year to 128.71 billion rupees ($1.55 billion) in the January-March quarter. Analysts, on average, expected revenue of 129.55 billion rupees, as per LSEG data.