And this definitely isn't a theoretical problem. People have had countfit items delivered by Amazon.com themselves because of the comingle issue (and third party vendors suspended because a different vendor tried to sell fakes, and they got comingled).

> For a given SKU Amazon takes the memory cards from its own inventory and inventory from all other resellers who have opted into the "Fulfilled by Amazon" program

No. Sellers have to opt-in to co-mingle, so it's certainly not "all other resellers".

Besides, I think co-mingle only applies to resellers's stock, ie Amazon stock and 3rd party sellers' stock aren't put together in the same basket -- although I could be wrong about that.

Answer: Amazon's

If you buy the one that's sold by Amazon it will come from the stock that's bought by Amazon.

That is not what this article claims =>

http://www.wsj.com/articles/on-amazon-pooled-merchandise-ope...

Do you have any sources which specify that Amazon treats it own inventory seperately?

They have no reason to. The idea of commingling is they can pick the best warehouse to ship from when a customer orders instead of (potentially) shipping across the country. They actually like commingling because it helps their logistics.

Generally Sandisk items are restricted, i.e. only authorized resellers are allowed to list them on amazon. (There's also a $1000 fee payable to Amazon to be allowed to sell them.)

So for Sandisk specifically this isn't a concern, although your comment applies to other, unrestricted brands.

Not sure that policy is working.

This listing came up in the top 10 when searching for "Sandisk 32GB": https://www.amazon.com/SanDisk-microSDHC-Package-Extenders-A...

The seller is "VP Distributor" and the brand is "Sadnisk" (sic). I don't see any links to see more info about the seller.

Click on the seller to get https://www.amazon.com/sp?_encoding=UTF8&asin=&isAmazonFulfi...

98% positive and 2250 lifetime feedback ratings means it's probably a good seller, just not authorized for sandisk and listed there to get around the rules. If someone took the time to report them the listing would be removed.

OTOH the same seller lists https://www.amazon.com/dp/B00M55C0VU, which I've confirmed on my account is restricted. So maybe they are authorized, and just listing on any ASIN they can find that matches the product? I've done that sometimes.

It doesn't look like customers are being harmed in this particular case, it's possible some unauthorized seller created the listing and VP distributor simply jumped on it at a later point, the first seller could be suspended now.

There's a d., the seller has to agree to co-mingle their inventory. Which a lot don't, since that means they can get dinged by another 3rd party's bad inventory....