By Svea Herbst-Bayliss

BOSTON (Reuters) - Billionaire hedge fund manager Daniel Loeb on Tuesday told clients that "idiosyncratic opportunities" have helped boost returns this year as a string of constant surprises has shaped markets, adding that more may be in store.

With next week's U.S. presidential election looming large, Loeb's Third Point hedge fund wrote to clients in a letter seen by Reuters that it is too soon to say what will happen and "we may see surprises on Election Day."

Calling the battle between Donald Trump and Hillary Clinton for the White House the "most disappointing and bizarre election in our country's history," the fund managers said it is impossible to say how the outcome will shape growth and interest rates.

For Third Point, closely followed in the investment community because of its pattern of delivering strong returns, "our short-term base case is for more of the same," the letter said.

The firm is not expecting a financial crisis or a recession, but noted "a clear path to growth seems elusive. We might soon long for 2 percent GDP growth."

The letter said that company earnings may be inflated at current levels, which creates both opportunities and challenges for investors, making it a stock-picker's market.

While many hedge fund managers have struggled this year, Loeb has put up relatively strong numbers and pointed to his team's successes. New bets made after the strong sell-off sparked by Britain's vote to exit the European Union, shifting to out-of-favor industrial commodities-related equities and bets on energy credit proved lucrative.

Through the end of September, the Third Point Offshore fund gained 7.2 percent, beating the average fund's 4 percent return.

Bets on corporate debt issued by Dell and Sprint also ranked among the year's top winners.

"We will often look for longer duration bonds in a company we believe has a visible catalyst for an improvement in its credit profile," the letter said.

The firm also benefited from early private investments in biopharmaceutical company Akarna Therapeutics, which was bought by Allergan in August, and Apigee, which provides analytics and management solutions to cloud computing services.

(Reporting by Svea Herbst-Bayliss; Editing by Dan Grebler)