TORONTO -- The Ontario Teachers' Pension Plan earned an 11.8 per cent return on investments last year, taking its net assets to $154.5 billion.

The result topped the fund's benchmark of 10.1 per cent return on investments and put the pension in a surplus for a second consecutive year. Its liabilities were 104 per cent funded, with a preliminary funding surplus of $6.8 billion at Jan. 1.

"These strong results were achieved in a turbulent investment environment," Teacher's president and chief executive Ron Mock said in a statement.

"With continuing low interest rates, intense competition pushing up asset prices, the slide in oil prices and resulting stock-market volatility, 2014 was not an easy year for investment success."

Teacher's invests and administers the pensions of 311,000 active and retired teachers in Ontario.

The plan's public and private equity investments earned 13.4 per cent for 2014 while its fixed income assets earned 12 per cent. Teachers' Private Capital earned 22.0 per cent.

Investments in the Natural Resources group lost 19.4 per cent, the fund's real estate portfolio -- managed by Cadillac Fairview -- returned 11.1 per cent, while its infrastructure portfolio earned 10.1 per cent.