Fiksu (http://www.fiksu.com), a mobile app user acquisition platform spanning the entire mobile ecosystem, says the iPhone 4S launch caused a large spike in mobile app downloads.

The Index experienced as much as a 70% increase in download volume during the iPhone 4S launch weekend and 40% increase in download volume during post-launch, when compared to the pre-launch time frame of the new iPhone's availability during October. Fiksu also observed a notable increase in organic downloads: up 75% during the launch and settling in at 54% post-launch.

"As predicted, October was a frenzied month; the availability of the iPhone 4S weekend launch caused an unprecedented surge in app downloads, providing great opportunity in volume for mobile advertisers," says Micah Adler, CEO, Fiksu. "For mobile marketers seeking a window of extreme growth regardless of cost, the iPhone 4S launch presented a bonanza to secure large volumes of new users. But for those seeking to maximize value and ROI [return on investment], the best bet was to resist the temptation to join the initial rush. Our advice to cost conscious marketers was to wait it out for a week and then take advantage of the efficiencies in heightened volumes at significantly lower costs."  

The Fiksu Indexes measure monthly fluctuations in competition for rank in the app stores, and the cost to acquire loyal users. They're designed to help mobile app marketers benchmark their performance against industry averages.

The Fiksu App Store Competitive Index (which measures the average aggregate daily download volume of the top 200 free U.S. iPhone apps) increased overall by 29% from 3.8 million downloads in September to a record high of 4.91 million in October. Usually the Index captures mostly new app downloads but, given a new device launch, this month the Index also recorded many existing apps being added by people upgrading from their previous iPhone model. Factoring this in, the likely net volume is 4.5 million new app downloads.

During the peak weekend of new iPhone sales, mobile marketing costs remained high, then fell in the weeks that followed due to decreased costs in traffic. By the end of October, the Fiksu Cost per Loyal User Index netted out to US$1.47. Marketers taking advantage of the immediate post-launch cost efficiencies saw a 12% decrease -- a 17 cent drop -- in cost per loyal user when compared to September's all-time high of $1.64.