How can I determine which stores are regarded as supermarkets for a rewards credit card?
Credit card companies organize types of businesses into different categories. (They charge different types of businesses different fees.) When a business first sets up their credit card processing merchant account, they need to specify the category.  Here is a list of categories that Visa uses. Grocery stores and supermarkets are category number 5411. Other types of businesses, such as the examples you provided in your question, have a different category number. American Express simply looks at the merchant category code for each of your transactions and only gives you rewards for the ones in the grocery store category. It's all automated. They likely don't have a list of every grocery store in the US, and even if they did, they would probably not provide it to the public, for proprietary reasons. If you are in doubt about whether or not a particular store is in the grocery category, you'll just have to charge it to your card and see what happens. Often, the category of transaction will be shown for each transaction on your credit card's website. Each company that has an account with the credit card network has to classify themselves as a particular type of business.  The credit card company uses that classification to catagorize the transaction on your statement. If you buy a T-shirt at a grocery, amusement park, gas station, or resturant; the transaction will be labeled by the vendor type.  Look at recent credit card statements, even if they are from different cards, to see how the stores you want to know about are classified. Looks like a user-contributed list is the only good solution to this question, so I'll start one by making this answer community wiki, meaning anyone can edit it. We only aim to add major chain, not every mom&pop store (which probably don't qualify). The rewards details page looks like this:  The lists are in alphabetical order. Contact AmEx. They are the only ones who might have a current list.
Although this scheme is likely to get shut down rather quickly by either your broker or credit card company some points you seem to have missed out on. Properly timed you should be able to get ~55 days of grace period (30 day billing cycle + 25 day grace period) assuming you pay everything off every month and charge immediately following the statement date.  You will need to avoid certain card issuers that code all transactions with financial institutions as cash advances (Citibank in paticular). If it is possible it would be in your best interest to lower cash advance limits to 0 to avoid any chance of cash advance fees. If your credit card attempts to process it as a cash advance the transaction will just be declined and you won't be out anything. Otherwise one cash advance fee will eat several months worth of profits. As far as investments with guaranteed principal goes the only thing you can realistically do is money market accounts and maybe treasury notes. Anything else and the short term price fluctuation may leave you high and dry. If this scheme were to work you would be much better off attempting to get rewards for the purchases than anything you could invest in. If you used a 2% card and churned it every month you would be looking at a 24% return on credit card rewards. Even 1% rewards gives you a 12% annual return which is going to beat anything you could invest the money in. The 'store card' that Amazon offers gives 5% back on Amazon purchases. Some time ago, when I realized how much of my spending was going through Amazon, I chose that card over this one.  If you want the card, that's fine, but if you are going to play the reward game, there are far higher bonuses available for card signups. No, it's not a scam. Many stores will offer a discount at the register the day you sign up for there card. In general, the store cards should also give a discount when used at that store, or airline for that matter. Assuming I only use it to buy things I can afford (which I trust   myself to do), essentially treating it as a debit card, is this a good   idea? This is definitely a good idea. From my own experience, before I got my first credit card through my local bank (age 18), I tired to apply for a card that has cash back rewards and was rejected because I didn't have any credit history. After I had the card from my bank for 6 months, I applied for this Capital One card that I've had ever since. I actually just did that with my Chase Freedom card. They rotate categories every 3 months, and from April-June it was 5% back at grocery stores.  So I bought a ton of gas cards and got my 5% back.  Next I figured out I would be clever and buy a ton of store gift cards (grocery gift cards) right at the end of the quarter, then use those in the future to purchase gas cards.  Well, I just tried that a couple days ago and discovered the store refuses to sell a gift card if you're paying with a gift card!  So now I'm stuck with $1,000 in grocery cards until I use them in actual grocery purchases haha One of the things about this grocery store is they partner with a gas station on their rewards program.  They offer 10 cents off a gallon with every $100 spent in store, and they double it to 20 cents off a gallon if you buy $100 in gift cards.  Then on the back of the receipt is a coupon for 10 cents off per gallon -- which they double on Tuesdays.  Unfortunately I think I'm one of the only people that takes this much advantage of the program  :-/ Side note: I actually just changed the billing cycle of my Chase Freedom card to end on the 24th of the month.  That way I can charge a bunch of rewards in the final 6-7 days of the quarter.  And if I have a $0 balance on the 24th, my bill isn't due for 7 weeks -- interest free!  And Chase Freedom has never cared if you purchase gift cards with their quarterly rewards program.  I also gave them a courtesy email giving the specific store and $$$ amount that was going to be charged, and of course they still called me with a 'fraud alert'... We've had a Costco membership for at least 15 years and only buy a few things there: paper goods (t.p. and paper towels), laundry detergent, and the contents of food bags my wife assembles to hand out to people who look like they could use some sustenance -- peanuts, Slim Jims, granola bars, peanut-butter crackers, etc.  We shop there *maybe* twice a month, tops. Precise in-store merchandising is critical to the success of your store or product. Gaps in execution can lead to wasted time, disorganization, a poor customer   experience, and lost sales. FreshSource specializes in the placement and line expansion of retail food products in supermarkets throughout the United States (Safeway,   Savemart, The Nugget, Raleys, etc, etc, etc). We represent Taylor Farms, Foxy, Green Giant and dozens of successful brands. if you need in store merchandising and   retail sales, look no further than FreshSource. The banks don't have to pay for credit card rewards. The merchants end up footing the bill. The merchants that accept credit cards pay from 2-4% in fees on the credit card purchase. Those fees go to support the rewards programs. The merchants also take on most of the risk during a credit card transaction (although the credit card companies would have you believe otherwise).  If a thief uses a stolen card to purchase a camera from Mike's Camera Shop for instance, any funds the merchant received will be taken away from the merchant. In addition, the merchant will be hit with a chargeback fee (usually around $20-$60). Finally, since the card was stolen, the merchant will never get their merchandise returned, so Mike's Camera is out the camera as well. No camera, no funds, and a $60 fee to boot. The credit card issuers make $60 on the chargeback fees and have no liability. A *lot* of big companies offer credit cards. And it makes total sense. For example, if you have a Macy's card, you get access to special discounts that you wouldn't normally get. It saves the consumer money and builds loyalty to the brand. Same for Southwest credit cards. It's a completely normal move.  EDIT: Also, Uber doesn't actually have to do much - it's the issuing bank that manages the program. *Most* of the branded credit cards you see are Chase, BTW. Amazon and Southwest are both run by Chase.