When the chips are down, it sometimes spells trouble for the broader market, and that's what's worrying some investors this week. Several semiconductor companies are stumbling over their own problems, but collectively the sector's sloppy performance and increasingly cautious outlooks are ringing warning bells for technology and the broader stock market. Advanced Micro Devices was among the biggest casualties, down 15 percent on Thursday alone. The VanEck Vectors Semiconductor ETF, lost 6.7 percent on Wednesday, its worst decline since the financial crisis in November, 2008. Even after a bounce on Thursday, the chip ETF was down 14 percent for October heading into Friday's trading. But the chip sector started to roll over versus the S&P 500 in September even as the broader market went on to hit another record later that month.

Chip ETF begins falling vs. S&P 500 in early September:

Source: Koyfin.com Texas Instrument's cautious warning set the tone earlier in the week, and that raised concerns across the market about the outlook for earnings in the fourth quarter and next year. Intel reported better-than-expected earnings Thursday afternoon and raised its outlook for the year, but it was set to open just slightly higher on Friday. "Semiconductors fall into pretty much every industry," said Dan Niles, founding partner of AlphaOne Capital Partners. He said warnings from semiconductor names are not new, but Texas Instrument's comments had more of an impact when it warned about a slowing in all its end markets, which includes autos and aerospace. "You can look at a company like Texas Instruments and they were sounding great on the conference circuit until mid-September. This was the first time they missed on revenues since the December quarter of 2015," said Niles. "When they're cutting back orders hard going into the holiday season, which is when most of the companies have huge sales, ... that gives you a pretty powerful sign that there's probably something going on." AMD's problems were in part due to expectations that it would continue to see strong revenue growth from cryptocurrency miners while others in the business did not. It also was a stock that had continued to climb while others fell hard.

'Signaling something'