MUMBAI: Life Insurance Corporation of India will soon buy 7 per cent equity in IDBI Bank through a preferential share issue, taking its total exposure to 14.9 per cent, as a first step in taking majority stake in the state-owned bank.IDBI Banks board of directors will consider the proposal for seeking shareholders approval through postal ballot for preferential issue to the state-owned insurer on August 31, the bank said in a filing to the Bombay Stock Exchange (BSE) on Tuesday.IDBI Bank on Tuesday received a letter from LIC giving its in-principle approval for subscription of the equity shares not exceeding 14.90 per cent of post-issue capital of IDBI Bank at any point of time, the bank said in the filing.