Apple (NASDAQ:AAPL) stock outperformed the S&P 500 this week, with a gain of 2.9% compared with the S&P 500's 1.8% rise. Why the big gain? What other Apple stories made headlines this week? Let's dig in.

iPhone 5c. Apple is bringing the iPhone 5c and 5s to China Mobile's network network in January.

China Mobile, finally!
All of Apple's gains during the week took place Monday morning, when the market reacted to the weekend news that Apple had finally officially announced a deal with the world's largest carrier, China Mobile. It was finally official: China Mobile will begin selling the iPhone on its network on Jan. 17. The stock soared nearly 5% on Monday in response to the news.

The market's enthusiasm for the deal makes sense. China Mobile's customers account for 45% of the country's 3G subscribers. Even more, China Mobile's 2G subscribers, at 582 million, dwarf its competitors. This figure alone exceeds the combined total of China Unicom and China Telecom's mobile subscribers.

Already, China is a meaningful market for Apple. After Europe, Greater China is Apple's third-largest market. The region's Q4 sales accounted for 15% of Apple's total revenue during the quarter.

Analysts haven't been slow to chime in with estimates on the potential impact China Mobile could have in 2014. Of 17 analyst estimates compiled by Fortune's Philip Elmer-DeWitt earlier this week, the consensus was 19 million. Asymco's Apple guru Horace Dediu estimates Apple will sell a whopping 30 million iPhones to China Mobile customers in 2014. That's only 3.38 million short of the total iPhones Apple sold worldwide in Q4. 

I looked in this the potential impact China Mobile could have on Apple's bottom line.

iOS dominates Android
The week's other big Apple story was undoubtedly IBM's report on holiday shopping habits online. iOS, according to the report, accounted for more than five times the online sales that took place on Christmas Day than Google's Android. The data is intriguing given that Android is well known for its rapidly growing market share that actually exceeds Apple's in smartphones in the U.S, according to Kantar Worldpanel.

Even more, the disparity between purchases on iOS versus Android actually increased on Christmas Day compared with Black Friday weekend. On Black Friday weekend (including cyber Monday), IBM reported that 4.95 times as many sales occurred on iOS than on Android.

Other matters
Finally, I explained in an article earlier in the week why Apple is my largest holding going into 2014. Find out why I'm betting on the stock here.

Of the week's news, China Mobile was certainly the most notable. As I noted in last week's Apple roundup, if Apple couldn't work out a deal with the world's largest carrier, Apple would be missing out on an enormous opportunity. Fortunately, Apple and China Mobile made it work.