During the period, the company sold 18,000 own shares at a weighted average price of 1.065 levs per unit, it said in a statement.
As at end-September, Industrial Holding Bulgaria held 792,985 of its own shares, equivalent to a 1.02% stake in the company.
In June, Industrial Holding Bulgaria said it plans to repurchase shares equal to up to 10% of its capital within five years.
As at 1130 CET on Monday, Industrial Holding Bulgaria shares traded 0.87% higher at 1.04 levs on the Sofia bourse.
(1 euro = 1.95583 levs)