LONDON — Barclays PLC on Tuesday reported a fourth quarter profit of 6.9 billion pounds ($10.8 billion), more than eight times larger than a year earlier, due to gains on the sale of its Global Investors unit to a private equity company. The result compared to a net profit of 824 million pounds a year earlier and boosted the full-year profit to 9.4 billion pounds, more than double the previous year's 4.4 billion pounds. The fourth-quarter surge reflected a pretax gain of 5.3 billion pounds from the sale of Barclays Global Investors to BlackRock Inc. The sale and a revenue boost from the acquisition of Lehman Brothers U.S.