The group has lured Kenny Watson from Ignis Asset Management in Glasgow, and Dan Daldry from Scottish Widows Investment Partnership in Edinburgh. Both will report into Rod Davidson, head of fixed income.
Katherine Garrett-Cox, chief executive of Alliance Trust, claimed ATI was "establishing itself as a real contender in the fixed income market".
She added: "Fixed income is one of the three pillars upon which our product offering is built, ensuring that we have experienced and capable teams in these areas is a priority for the business and Kenny and Dan will play a critical role in this endeavour."
ATI, under fire two years ago from activist shareholder Laxey Partners for losing the group money, narrowed its losses from £2.7m to £1.7m last year, increasing assets by £100m to £1.5bn.
Last month it completed the transforming acquisition of Aviva Investors' sustainable investment team and £1.2bn of funds.
ATI's fixed income team runs a £322m monthly income bond fund, launched in June 2010, which is ranked 66th out of 78 funds in the sector over three years but 21st over one year, according to Investment Life & Pensions Moneyfacts.
The ATI website was not showing any performance figures for its funds yesterday but its most recent commentary on the fund, run by Stuart McMaster and Stuart Steven, said it had matched its benchmark in the second quarter of 2013.
ATI says five out of seven of its seven Sustainable Future funds have outperformed their benchmarks over a three-year period
New hire Mr Watson arrives after 15 years at Ignis, specialising first in UK smaller companies before moving to the fixed income team in 2004 where he was responsible for sub-investment grade bond portfolios including the group's high income bond fund.
Mr Watson started his career at KPMG before joining Murray Johnstone as a trainee fund manager in UK equities in 1994.
Mr Daldry has spent the last five years working at Scottish Widows Investment Partnership, ultimately as a portfolio manager on the SWIP Absolute Return Bond Fund.
He joined SWIP as a member of its graduate training scheme in 2008, going on to specialise in financials credit analysis.
Mr Watson will focus on credit and high yield, while Mr Daldry will provide the portfolios with financial credit analysis.
Rod Davidson, head of fixed income, said: "Today's appointments are significant in underlining our commitment to expanding the fixed income offering at Alliance Trust Investments. The team is now a good size and is well positioned to enable the company to push the fixed income business forward into 2014 and beyond."