How to get/transfer 4240 points to AAdvantage
 

Is it possible to transfer from Alaska or Delta to AAdvantage (even through 3rd party like points.com)?

Most airline miles can not be converted to other carriers miles directly. With that said, the use of a 3rd party as you mentioned will come at a steep cost to you.

In most cases, it's best to just suck up and buy them.

Even if you can find someone who would sell them to you (and advertising for something like that is prohibited on FT), the price you'd pay plus the transfer fee isn't likely to be much less than buying them.

You MIGHT check out some bonus offers, particularly multiple points per dollar spent on the AAdvantage shopping website, if there was something expensive you wanted to buy anyway.

Don't sell your points, upgrades, or any associated benefits/access. It's entirely against policy and could result in the termination of your participation in a given frequently flyer program.

On the balance 4200 points is roughly a few magazine subscriptions so you're not really 'losing' much anyway if you can't find a means to redeem them for travel.

OP isn't trying to save 4240 points but wants to know how to get 4240 points into account (presumably to redeem an award).

Easiest and fastest way is to buy them ~$150

Look at these to see if they help.
https://www.aa.com/i18n/aadvantage-p...earn-miles.jsp

This was a comment based on an earlier remark in this thread about engaging in any buying or selling miles transaction. Nothing to do with saving them.

I think the confusion is that we don't know if OP is trying to top off their AA account or has some orphan miles in AS or DL that they'd like to save by transferring to AA. I suspect the former, in which case your comment about not losing much as 4200 is just a few magazine subscriptions isn't really relevant.

I had correctly or incorrectly assumed the latter in which case the ability to move a few thousand miles around isn't really much of a loss and isn't worth more than a few magazines.

If you have enough Alaska miles, you might be able to redeem those for the AA flight that you want. Availability should be the same.

There is no efficient method of transferring miles between airlines, even those in the same alliance.