Shares of Mahindra & Mahindra (M&M) plunged 6% to Rs 2,666.45, its sharpest intra-day fall in seven months, on the BSE in Friday’s intra-day trade after the company announced to invest in the proposed rights issues of its subsidiaries, Mahindra & Mahindra Financial Services Limited (MMFSL) and Mahindra Lifespace Developers (MLDL).