This is a glimpse into his new world: On behalf of 25,000 financial institutions, MasterCard's worldwide network in 2007 processed 18.7 billion transactions totaling some $2.3 trillion. On an hourly basis, the network has to manage 140 million transactions, with a response time of 140 milliseconds per transaction. And 99.999 percent network availability is standard operating procedure.

All of this wasn't totally new to Reeg. He had served in the position on an interim basis since January 2008. And before that he was MasterCard's CTO. "So it was a fairly easy transition," he says.

Though the transition may have been a piece of cake, his job's demands are anything but. Ridiculous network requirements aside, Reeg is responsible for managing MasterCard's global IT environment, headquartered in St. Louis and with operations in 210 countries, preventing frauds and credit-card scams, innovating with transaction-processing systems and enhancing financial institutions' product offerings gleaned from MasterCard's data warehouse. (To read more about MasterCard's IT innovation and what Reeg's predecessor did, see "IT-Led Innovation at MasterCard.")

CIO.com Senior Editor Thomas Wailgum talked to Reeg about his biggest worries, how his credit-card data got compromised, and just how "Priceless" his IT staff is.

CIO: What are your new responsibilities?

Rob Reeg: There are five key functions I'm focused on: 1. Our global network and how those 18.7 billion transactions flow. 2. Making sure we leverage that network to provide very fast, reliable payment processing. 3. On top of that platform, how do we provide our customers with custom and differentiated payment solutions. 4. How do we provide support to customers as they use our products and services. 5. How do we leverage that gold mine of data that occurs when you have 18.7 billion transactions that you're processing.

MasterCard's Rob Reeg

Who are MasterCard's customers?

Reeg: Our customers are typically the banks. We're in what we call a four party model. There are card holders, who have a relationship with an issuing bank; so that's two parties in the model. On other side there are the merchants have a relationship with their bank, an acquiring bank. Those are the four primary stakeholders in any kind of payment transaction.

We sit in the middle, between the issuing and acquiring banks, making sure those payments occur as they should and then move the money appropriately.

How big of an infrastructure do you have to support and maintain? It must be huge.

Reeg: Actually from a pure server footprint standpoint, in the data center, we probably have fewer actual footprint servers because of techniques like virtualization that help us leverage one box to do multiple things.

Where it gets interesting is philosophically: We try to put [transaction] processing as close to our customers, the banks, as possible. When we talk about the global network, we have small servers that sit with the bank customers that connect to our network. What it does is it gives us intelligence there at the end of the network. So as a transaction comes through, we can take a look at that transaction and decide how do we best process that transaction for the benefit of all those four parties in the model.

As to processing, the majority of transactions we're looking at relate to how do we process them as fast as possible in the most accurate way. The way to do that is by peer to peer: If you're using your card in Europe, in London, say, and you swipe your card as you check out of hotel, we can route that transaction to the hotel's acquiring bank in London directly to your issuing bank and get that message back for approval without ever going through St. Louis or some big data center in the middle of all that.

You talk about competitive differentiators like that, but that message isn't going to consumers, who use the cards. So does that networking innovation message go to the banks?

Reeg: We obviously talk to banks and then we'll do pilots [with them]. For example, we just introduced our card we call PayPass that leverages contactless technology. We did a pilot with the New York Transit System and the bank that supports the transit system. So people take their PayPass card, touch it against the entry device or turnstile, and get into the subway, passing through very quickly.

So it's a combination: We'll work with banks and merchants, and with banks on programs they want to introduce to cardholders. Leveraging the data warehouse, we do help banks do targeted marketing and targeting rewards programs, for example, if a bank wants to do a special deal with a big electronics merchant to incent customers to use their card there. We may help them segment a portion of their portfolio that we believe, based on the data, would be interested in that kind of service.

When a consumer uses a MasterCard in a store, the transaction is usually seamless and fast. So what networking things happen in those seconds that I'm standing there at the counter?

Reeg: It's pretty interesting, because like you said, the vast majority of all payments you never really think about. It always works. It's like turning on the tap and expecting water to come out.

But what really happens is: You're at the hotel, and they have a card reader on their desk when you check out. That card reader is swiped or in the case of PayPass [is used as] contactless payment, and it transmits information off your card to the merchant. The merchant is then connected to their acquiring bank, and their acquiring bank takes that transaction, knows it's a MasterCard transaction and gives it to us. We take the transaction, look at how do we best route this transaction to get it approved and send the routing information off.