Celtic reduced their bank debt by £2million during the second half of last year, their interim financial results show.
Celtic made a pre-tax profit of about £180,000 while cutting the debt to just over £7million.
Turnover increased by 3.1% to £29.3million during the six months to December 31.
Celtic reported investment in football personnel of almost £4.5million, half of the figure for the same period last year, when they profited from the sale of Aiden McGeady among others.
Chairman Ian Bankier said: "At this time last year we reported a profit from player transfer activity of £13.2m. This year, the comparable figure is considerably less, at £3.15m.
"The key dynamic driving these interim results and our financial performance for the remainder of this financial year is our player investment and transfer strategy. We invested £4.44m in the first half of the year and have followed this with further acquisitions in the most recent January registration window.
"We can confidently say that the strength and depth of the player pool now available to the football manager is better than it has been for several seasons. This has been a conscious decision that the financial discipline of the past has allowed us to take.
"As a result, we have been able to enjoy the virtuous trilogy of being able to keep our best players, build and develop significant value in our player pool, and see improvements in football performance."
Celtic's Europa League reprieve helped increase turnover by almost £1million after they were reinstated following the exclusion of Sion before bowing out in the group stages.
Operating expenses rose in line with turnover while Bankier predicted a similar trading pattern in the first six months of this year.