Financial Performance After M&A: A Multi-Horizon Analysis of Indonesian Listed Firms

This study examines financial performance before and after mergers and acquisitions (M&A) among Indonesian listed firms. The sample comprises 134 M&A events involving 91 companies and 481 event-horizon observations. Twelve financial indicators are assessed one year before the transaction (t − 1) and one, three, and five years afterward (t + 1, t + 3, and t + 5). Population-averaged generalized estimating equations (GEE), using winsorized indicators and robust event-clustered standard errors, estimate differences relative to the pre-M&A benchmark. The analysis applies Holm adjustment to 36 prespecified horizon comparisons and examines sensitivity to raw data, sample composition, firm-level dependence, and calendar-year effects. Tobin’s Q declines at t + 1 and t + 3 relative to t − 1, with both differences remaining statistically significant after Holm adjustment in the primary and calendar-year fixed-effects specifications. Evidence for other indicators is less consistent, and no t + 5 comparison survives the primary Holm correction. These findings suggest that market valuation responds differently from accounting and liquidity measures across post-transaction horizons. Because the study lacks a matched non-acquiring comparison group and comprehensive transaction-level controls, the estimates describe longitudinal associations rather than causal M&A effects.