US stocks fell on Friday as investors assessed the latest economic data after more and more policymakers made cautious comments on the market.

The S&P 500 fell 0.2%, while Dow traded lower partly due to pressure from Apple brought by a court order to change the way it receives money from its App Store.

Meanwhile, gold posted its first weekly decline since early August after producer price data came out and the US resumed controversy over when the Federal Reserve will taper stimulus.

Markets have been volatile as the continued spread of COVID-19 undermined economic recovery and lifted supply-shock-fueled inflation, despite central banks confirming an adaptive stance. In the US, stocks have slipped amid mixed economic data and a lack of clarity on the timing of Fed tapering. Data released last Friday also showed that PPI rose more-than-expected last month.

Fiona Cincotta, senior financial markets analyst at City Index, said investors seem to be particularly monitoring the rise in Covid cases, economic growth, inflation rate and the schedule when the Fed will tighten monetary policy.

In fact, this week, analysts from nearly every major Wall Street bank issued a nervous report on the US stock market. Common themes in their analysis include historical valuation extremes, a nearly continuous rally for seven months, an economy that looks soft, and the inevitable cut in Fed stimulus.

Apple has been the worst performer, losing the most since mid-August. As noted above, this is due to a court order saying the company should allow app developers to direct consumers to use external payment methods.

On a different note, there are again trade tensions with China. The Biden administration is reportedly weighing a new investigation into Chinese subsidies after US president Joe Biden called on China's Xi Jinping to cooperate by phone.