Friday's market plunge finally broke the S&P 500's flat summer, but there could be one indication that the market slide is set to continue.
While the S&P 500 fell 2 percent during Friday trading, bond prices continued to drop, pushing yields higher. That spells bad news for stocks, according to Evercore ISI technician Rich Ross, who turned to the charts Friday on CNBC's "Trading Nation" to explain why.
Ross charted the TLT, which tracks longer-term Treasury bonds, to show what he sees as a further drop in bond prices. A decline in bond prices means higher yields, which can have an inverse relationship with stocks. While that isn't always the case, Ross sees indications that such an inverse relationship could be at play, using Friday's trends as proof.
"We see those bond prices breaking down and they're testing that 100-day moving average," said Ross. "This breakdown from that formation has corresponded with a backup in yields from 1.33 roughly in the 10-year to 1.66 this morning. That's bad news for stocks, which have climbed on the back of those low interest rates."
How much farther could bond prices fall? To make that prediction, Ross points to the appearance of what he calls a "pennant" pattern, a period of consolidation in the TLT that could signal a break to the downside. The height of the pattern was at $144 and the low point was at $138, which leads Ross to conclude that a break downward would see the TLT tumble another 6 points.
In other words, the TLT could hit $132, and if Friday's trends are any indication that means stock prices could fall even further as well.