Beijing - Disruption reaps disruption.
Just look at the changing fortunes of Alibaba's innovative online money-market fund.
As rivals have rushed to join the craze for online investing, the returns for being first off the mark are fading.
Total assets in Zeng Libao, the fund owned by the Chinese e-commerce group's financial affiliate, shrank by 9 percent between June and September.
That's a big change for a fund that almost tripled in size between January and March by offering interest on cash that internet shoppers would otherwise leave idle.
It might just be that the novelty is fading.
Falling rates in the interbank market, where some of Zeng Libao's funds end up, have also taken out some of the heat.
The rate at which banks lend one-month money among themselves was as high as 8 percent in January.
Now it's just 4.2 percent.
Graphic: Alibaba's market fund hits a glass ceiling: http://link.reuters.com/jak33w
The arbitrage that drove funds into Zeng Libao in the first place, however, is still there.
Bank depositors are limited to rates of 3.3 percent on one-year savings accounts.
Alibaba no longer offers more than twice that rate, but the 4.1 percent it does pay, with near-instant withdrawal, is better than most available alternatives.
The money market industry's overall net assets grew more than 10 percent between June and August.
One problem for Alibaba is that good ideas spread fast in China.
Rivals Tencent, Baidu and JD.com now offer money-like funds, as do banks like China CITIC.
Alibaba's fund has taken a less aggressive approach to investing in longer-dated assets than its competitors.
What its investors get back is thus slightly lower, but slightly safer.
Some of the shrinkage may also be due to customers spending more of their cash in Alibaba's online stores.
Zeng Libao added 20 percent more users in the third quarter, although their average balance fell by more than a fifth.
More innovation might add back some of the magic.
Homebuyers can now use Zeng Libao to make deposits on houses, while still collecting interest.
The fund manager that runs Zeng Libao has even launched a social network.
But if the glory days are over, Alibaba can always content itself with the knowledge that thanks to its efforts, China's savers are better off.
(The author is a Reuters Breakingviews columnist. The opinions expressed are his own.)
By John Foley https://twitter.com/johnsfoley - Reuters