Other U.S. bellwether companies were showing mixed results in early trading on Thursday, Jan. 3, following Apple Inc.'s (AAPL - Get Report) bombshell announcement that it won't meet its own fiscal first-quarter revenue forecasts.

Apple was down more than 9% in early trading on Thursday after the tech giant cut its forecast for fiscal first-quarter revenue - the holiday quarter - thanks in part to slowing sales in China.

U.S. companies that also rely on China and Asia as a component of their sales also saw early downward pressure on their shares. Boeing Co. (BA - Get Report)  was down nearly 2%, or $6.01, to $317.80, Caterpillar Inc. (CAT - Get Report) was down 2.4%, or $2.97, to $123.41, and Johnson & Johnson (JNJ - Get Report) was down 0.78%, or 99 cents, to $126.70.

Apple announced through an open letter from CEO Tim Cook on Wednesday that it now expects December quarter (fiscal first quarter) revenue of $84 billion. That's down about 5% annually and below prior guidance of $89 billion to $93 billion, as well as a FactSet analyst consensus of $91.3 billion.

Ongoing trade tensions between the U.S. and China as well as slowing economic growth in both economies has raised concerns among investors that sales and net earnings of American companies that sell and export east will be weaker than currently anticipated.  

"U.S. economy volatility looks set to continue in 2019, with a resolution to the US-China trade dispute likely to be a protracted affair," noted CMC Markets' chief market strategist Michael McCarthy. "Moves in U.S. markets reverberate around the world, and in a fluctuating market, rewards are likely to go to those investors that stay active."