Stock indices were nearing record high levels in September until October and the fourth-quarter began. In the last two days, the U.S. markets have fallen broadly as investors began showing concern about fresh signs of an economic slowdown.The Dow Jones industrial average’s losses deepened on Wednesday, bringing its two-day decline to 827 points. The Dow has lost 3% so far this quarter, already wiping out the 1.2% gain of the third quarter. It still remains up 11% for the year.EconomyThe drop in the Dow began after a key measure of U.S. manufacturing saw its lowest reading in more than 10 years on Tuesday. September’s reading of manufacturing data from the Institute of Supply Management (ISM) came in at 47.85% – the second consecutive month of contract for the index. Any reading of the ISM index below 50% signals a contraction.Shortly behind last month’s slowdown in manufacturing was the month’s private payrolls report on Wednesday, which revealed that the pace of hiring is easing as the labor market continues to tighten. ADP and Moody’s Analytics said companies hired an additional 135,000 workers in September, a slowing from 157,000 hirings during the previous month. What’s more, the August numbers were revised sharply lower, as there were 195,000 more workers previously reported for the month.ImpeachmentThe two economic warning signs come as President Donald Trump faces a push for impeachment for Democrats, which want to see Trump removed for allegations that he abused his power as president. The possibility of impeachment has been negative for U.S. stocks; although some investors say that if Trump is removed there may be a Clinton-like rally in equities.One of the main concerns from investors is that impeachment proceedings will undermine trade negotiations, especially with China. Last week Washington policy analysts warned clients that an impeachment inquiry is likely to waylay the U.S. from passing the United States-Mexico-Canada Agreement (USMCA) or coming to a resolution with Beijing. With the escalating trade war weighing on U.S. companies, Wall Street remains concerned that Trump will not be able to reach a deal that would result in the removal of the tariffs on billions of dollars worth of imports.Technical breakdownThe S&P 500 fell below its 50-day moving average on Tuesday, a key technical indicator watched by analysts. Bespoke Investment Group noted on Wednesday that, for the first time in the index’s history, the S&P 500 was set to begin October with back-to-back drops of more than 1% each. Additionally, a drop of 2.75% would be the fourth worst start to the fourth quarter for the S&P 500 in its history.Both the Dow and S&P 500 finished the third quarter of the calendar year just below the all-time highs hit in July so this has been a rapid turn of events.