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July 17, 2026 · week in review

IBM's 26% Slide and a Chip Selloff Drag the Week Lower Despite Broad Gains Elsewhere

The S&P 500 fell 1.55% for the week even as most of its members rose, while an outsized IBM decline sank the Dow and semiconductor weakness pulled the Nasdaq 100 down more than 4%.

The S&P 500 lost 117.70 points this week, or 1.55%, closing at 7,457.69 on July 17. That decline came with breadth that ran the other way: 277 of the index's 503 members finished the week higher. A negative index return alongside a majority of positive stocks is the signature of a handful of large names doing outsized damage while the rest of the market held up or gained. Concentration for the week measured 47%.

The S&P 500 through the session

The drag came almost entirely from semiconductors. NVIDIA subtracted 22.76 points on a 3.86% decline, Micron gave back 16.54 points on a 13.31% drop, Broadcom cost 15.85 points falling 7.29%, AMD subtracted 11.53 points on an 11.14% decline, and Sandisk fell 29.29%, pulling out 9.75 points. Offsetting some of that, Apple added 30.19 points on a 5.84% gain, with Microsoft, ExxonMobil, Palo Alto Networks, and Chevron also contributing positive points.

S&P 500 attribution map, cell size = points contributed

The Dow

The Dow fell 491.01 points, or 0.93%, to close the week at 52,146.00. Seventeen of its 30 members rose, another week where more stocks were up than down while the index itself fell. Concentration ran to 191 for the Dow, well above what the S&P showed, a sign that a small number of names moved far more than the net index change and were largely offset by others.

The Dow through the session

This is where the week's story diverges sharply from the S&P narrative. IBM alone subtracted 445.12 points on a 26.04% decline, the largest single driver anywhere in this week's data, with Caterpillar close behind at -428.71 points on a 7.57% drop. Alphabet, Cisco, and Boeing also weighed on the average. Travelers was the biggest offset, adding 178.66 points on an 8.87% gain, followed by Apple's 109.48 points, Chevron, Goldman Sachs, and Visa. Unlike the S&P and Nasdaq stories, chips barely register here; this was an IBM and Caterpillar week for the Dow.

Dow attribution map, cell size = points contributed

The Nasdaq 100

The Nasdaq 100 was the week's weakest major index, down 1,232.45 points, or 4.13%, to 28,592.66. Breadth was the thinnest of the three: only 43 of 103 members advanced, and the equal-weight move of -3.25% shows this was not just a few megacaps falling, weakness ran wide across the index's constituents.

The Nasdaq 100 through the session

Space Exploration Technologies led the decline, subtracting 176.24 points on a 14.67% drop, with NVIDIA, Micron, and Broadcom again showing up among the largest drags, joined by Tesla's 64.49-point contribution on a 6.6% decline. Apple was again the largest offset, adding 166.03 points, with Microsoft, Amazon, Palo Alto Networks, and CrowdStrike also positive. The same chip names that hurt the S&P did more damage here given their larger index weights, while Apple's gain, though sizable in points, was not enough to turn the index positive.

Nasdaq 100 attribution map, cell size = points contributed

The sectors

Across the eleven sectors, the split was wide. Energy, Real Estate, Consumer Staples, Financials, and Health Care all closed the week higher, while Utilities, Materials, Communication Services, Industrials, Consumer Discretionary, and Technology all fell, with Technology's decline dwarfing the rest.

The 11 sectors by move, top contributor named

Energy was the week's strongest sector, up 4.72%, led by ExxonMobil, which contributed 0.68 points on a 6.13% gain.

Energy: what moved it

Technology was the weakest by a wide margin, down 5.49%. Sandisk was the sector's top driver, subtracting 1.04 points on a 29.29% decline, part of the same semiconductor weakness that showed up across the S&P and Nasdaq 100 sections above.

Technology: what moved it

Percentile context for this week's moves was not included in the payload, so no move here can be labeled large against the past year's distribution. What the data does show plainly is a week where the median stock across the S&P 500 held up far better than the index itself, while both the Dow and Nasdaq 100 carried more damage from single names, IBM in one case and the chip complex in the other.

The numbers

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Compiled by the WMTMT attribution engine from the session's official data · built by the founders of Babylon Burns