NEW YORK (Reuters) - U.S. corporate reporting season is expected to show lackluster profit growth, and it has already gotten off to a bumpy start, with big banks kicking off the fourth quarter to mixed investor reaction so far on the stock market.

FILE PHOTO: Traders work on the floor at the New York Stock Exchange (NYSE) in New York, U.S., January 14, 2020. REUTERS/Brendan McDermid

With the vast majority of the S&P 500 still yet to report, forecasters expect fourth-quarter earnings to be down 0.5% from a year ago, according to IBES data from Refinitiv.

“Q4 is probably the last quarter where the market kind of gives a pass to earnings,” said Dave Lafferty, chief market strategist at Natixis Investment Managers in Boston.

Among the large banks, JPMorgan Chase & Co and Citigroup reported results that beat expectations, while Goldman Sachs Group Inc and Wells Fargo & Co missed.

Within the S&P 500, estimates vary widely for sector performance in the fourth quarter. Financials and utilities companies overall are expected to have tallied double-digit profit growth, while energy, industrials and consumer discretionary are seen reporting declines.

(GRAPHIC: Q4 earnings expectations, by sector: )

Many investors say they are more focused on corporate outlooks, with stronger 2020 profit growth needed to help justify big gains in the stock market. As of Wednesday, consensus analyst estimates called for a nearly 10% rise in earnings this year, according to Refinitiv.

“There is a lot more optimism priced into the 2020 numbers than there has been priced into the 2019 numbers,” Lafferty said.

(GRAPHIC: 2020 earnings estimates, by sector: )

With 2019 being a relatively sluggish year for profits, the stock market’s ascent reflected a rising valuation on equities.

The S&P 500’s forward price-to-earnings ratio has climbed from roughly 14 times to start 2019 to about 18 times by the end, an increase that investors attributed largely to interest rate cuts from the Federal Reserve.

Investors say such extensive P/E expansion is unlikely again this year, putting pressure on corporate earnings to come through.

“We expect earnings growth to drive stock market gains in 2020,” LPL Financial Chief Investment Strategist John Lynch said in written commentary on Wednesday. “With valuations elevated, corporate America will probably have to do the heavy lifting to get stocks much above current levels.”

(GRAPHIC: US stock market valuation: )

Particular focus will be on results from market heavyweights Apple Inc, Microsoft Corp, Alphabet Inc and Amazon.com Inc, which alone represent about 15% weighting in the benchmark S&P 500.

Those stocks, particularly Apple and Microsoft, contributed a significant chunk of the S&P 500’s 31.5% total return last year, according to Goldman Sachs data.

(GRAPHIC: The shadow of market heavyweights: )