Which the companies expect to close by the end of the year. Elon Musk-led Tesla Motor  TSLA 0.46%  said on Monday its proposed acquisition of SolarCity  SCTY -1.54%  could be delayed due to shareholder lawsuits challenging the deal. The company said four lawsuits were filed in Delaware between Sept. 1 and Sept. 16 and a potential injunction on the proposed $2.6 billion merger could delay the closing of the deal. The lawsuits allege, …