Bears extended their grip on Thursday, dragging the S&P 500 index futures to a fourth consecutive losing session as expectations of a rate increase continued to climb.

Similar to Wednesday, bulls held the line at unchanged overnight, and this time they also set the day’s high at 7666.25. By the morning hours, however, the index futures had faded back into the red. August’s Producer Price Index (PPI) report came out mostly within expectations at 0.4% MoM, but it also included revisions of +0.1% to both the Core and headline MoM numbers for July. Following the release, the probability of a September rate increase went up, according to CME FedWatch, and bears quickly took the index futures another leg lower to the psychological 7600 area.

Once the regular session began, the opening chop saw bears carve out a new low of 7585.50 before bulls could strike back. Bulls reclaimed the 7600 handle but were unable to hold onto any major gains beyond that point. For the remainder of the day, bulls fought to hold support near that level, and the action settled into chop in that area. The session concluded somewhat near the day’s low at 7598.50, losing 45.25 handles.

Friday, market participants can look forward to August’s CPI data at 8:30 AM ET, along with only a small handful of mostly benign earnings reports in the morning.

Among the top components of the index, Apple Inc (NASDAQ: AAPL) emerged as the biggest gainer a day after its latest iPhone announcement. The tech giant advanced by $11.23 or 3.56% to close at $326.57 for the day.

That performance was over 4% better than the cash index’s decline of 0.60%.

Conversely, the biggest loser ended up being NVIDIA Corp (NASDAQ: NVDA). For the day, the chip designer declined by $5.31 or 2.37% to close at $218.36.