The savings arm is the biggest contributor to the head count of around 200 at ATS's headquarters in Dundee, employing 126 directly.
The group, headed by Katherine Garrett-Cox, has yet to reveal its next move, following a marketing campaign which has included high-profile outdoor advertising at airports as it promotes the attractions of its unusual fixed-fee platform model.
Shareholders were told at last month's annual meeting in Dundee that ATS had returned to profit last year, and was now profitable on a monthly basis, helped by higher pricing.
An ATS spokeswoman said: "Alliance Trust Savings confirms that it has conducted a review of its marketing operations and has taken the strategic decision to outsource the majority of this work going forward. This has unfortunately resulted in a small number of roles being placed at risk of redundancy and we are currently in discussions with the affected employees. In some cases, there may be potential for redeployment elsewhere in the business."
It follows the announcement four months ago that ATS was outsourcing its platform technology to GBST having previously provided its own. A company source said the moves were driven by the need to be efficient and flexible and not by business problems.