Nice work! Yes, the reality is that the sector is down below 60%...

Nice work! Yes, the reality is that the sector is down below 60% on average but there are tiers based on company level performance. AGY struggling on that front until they get the plant sorted. I wrote some Python code for sector analysis and here is its output for lithium. Somewhat similar findings to your efforts above.

* Included Ganfeng and Tianqi, some NYSE stocks and lots of ASX. I tried to only include ones with complete datasets. That standard deviation spike right at the end is some missing data in the Yahoo finance server I'm pulling the data from at the end of some datasets. If it keeps up, I'll have to fix the code to filter it out in the next code iteration.
* Basically it calculates the high for each stock within the shown range, works out the change from the high, and then the sector mean (in black) and its standard deviation (in red). Simple.
* Standard deviation shows nicely the bifurcation between these tiers of sector companies. Namely that as the commodity price tanks, the lower tiers (non-producers/explorers etc) tank first as expected and the established low-cost producers, on average, hold up the longest. You can also see that following a bottom (where the standard is low as everyone has maximally tanked from their highs), the higher-tier producers tend to improve first increasing the standard deviation.

I'll probably replace my plots with this as the others take time to mess about in Excel and this is now automated for each sector. Also this isn't restricted to end of month either. So still looks like the low was in Feb 2024 with correlates roughly to the carbonate spot price low.