VanEck's semiconductor ETF rose 4.9% while iShares' rose 9.4%

VanEck Semiconductor ETF, SMH, rose 4.9% in the week ending Nov. 13, and iShares Semiconductor ETF, SOXX, rose 9.4%.

Among 25 semiconductor ETFs, the median gain was 7.9%, and none finished lower. SMH was below that median. SOXX was above it.

VanEck's holdings as of Nov. 6 put Nvidia at 20.8% of SMH. iShares, as of Nov. 4, put Nvidia at 8.2% of SOXX.

The two indexes do not allow the same Nvidia weight. SMH tracks the MVIS US Listed Semiconductor 25 Index, an index of 25 U.S.-listed semiconductor companies. At each quarterly reset of its weights, it can put as much as 20% in one company. SOXX tracks the NYSE Semiconductor Index, an index of about 30 companies that caps each one at 8% when the weights are reset.

The caps apply at the reset, not on every trading day. Nvidia's weight was a little above both.

Nvidia fell 12.7% over that week, and most of the drop had already happened before Thursday's announcement. The stock fell 4.3% on Monday and 5.5% on Tuesday. By Tuesday's close it was down 9.5% from the prior Friday. It rose 2.9% on Wednesday.

On Thursday Nvidia said Jensen Huang had resigned as president, chief executive and a member of the board, effective immediately, and named Colette Kress, the chief financial officer, interim chief executive. The stock fell 4.3% on Thursday and 2.0% on Friday.

Nvidia's heavier weight does not account for the whole difference between the two funds. SOXX also held more of the stocks that rose. As of Nov. 4, Advanced Micro Devices was 9.4% of the fund and Broadcom was 7.9%. As of Nov. 6, those two were 5.4% and 5.7% of SMH. AMD rose 18.9% for the week, and Broadcom rose 18.2%.