THE business sentiment among Malaysian firms has depreciated in the third quarter of 2021 (3Q21) after four consecutive quarters of improvement, according to Dun & Bradstreet (M) Sdn. Bhd (D&B Malaysia).In its 34th report, it said the Business Optimism Index (BOI) dipped marginally from -6.81% in 2Q21 to -8.06% in 3Q21.On a year-to-year (YoY) basis, the BOI climbed moderately from -13.33% in 3Q20 to -8.06% to 3Q21.