I don't recall recent 1st Chainmails being particularly weak, either - the recent auctions leading up to the previous value a few months ago, rather than a large number of high quality copies well under $1,000 which should(?) have been required to plunge the valuation the other way?
($1,813 down to $1,131 for theoretical (never seen) NM)

And I was more-or-less happy about the previous update, bar a few presumed-missed auctions and suchlike.

The price drop was a mistake.  Rather, an error in the code that was used to arrive at the values.  I've been aware of it, but haven't had the time to fix it -- hopefully in about two weeks, I will.

Foul

Theoretical = none on my list of eBay sales*, IIRC, that would've gone into the estimated valuation number-crunching. i.e. That NM valuation is a theoretical value derived from the lower graded sales...

(*Either that or I'm a much harsher grader than most. )

The values continue to decrease.  

I don't own any of those rare items, so I don't care as much as one would initially assume. As stated in the Random thoughts thread, I am currently content with my white box and OD&D reprint.  

Alrighty, the problem with the calculation software has (hopefully) been sorted.  Corrected values have been posted to the Indexes, and all should be fine now.  Note that some of the wild price swings (the up/down percentages) are due to the difference between the corrected value and the old, incorrect value.  The percentages will normalize next month.

Also, you'll notice a change to the Value Updated column on the Indexes; the month has been added to the year for when an item's value was last updated.  If there are no new auctions to factor into a valuation, the Value Updated column won't update.  I set the last-updated time to Jun 2015 as a baseline for all items, with the exception of a few that I used for testing (and which are showing Jul 2015).  It may take a month or two for certain auctions to factor into an item's value; the Valuation Board member responsible for that item needs to actually grade and enter the data into the system in order for it to be computed.  The system then calculates and updates values on the 10th day of each month.

Regards,

Foul

Those have gone up considerably in the last few years.