We examine open market stock trades by registered insiders in about 3700 targets of takeovers announced during 1988-2006 and in a control sample of non-targets, both during an 'informed' and a control period. Using difference-in-differences regressions of several insider trading measures, we find no evidence that insiders increase their purchases before takeover announcements; instead, they decrease them. But while insiders reduce their purchases below normal levels, they reduce their sales even more, thus increasing their net purchases. This 'passive' insider trading holds for each of the five insider groups we examine, for all three measures of net purchases, and is more pronounced in certain sub-samples with less uncertainty about takeover completion, such as friendly deals, and deals with a single bidder, domestic acquirer, or less regulated target. The magnitude of the increase in the dollar value of net purchases is quite substantial, about 50% relative to their usual levels, for targets' officers and directors in the six-month pre-announcement period. Our finding of widespread profitable passive trading by target insiders during takeover negotiations points to the limits of insider trading regulation. Finally, our finding that registered insiders of target firms largely refrain from profitable active trading before takeover announcements contrasts with prior findings that insiders engage in such trading before announcements of other important corporate events, and points to the effectiveness of private over public enforcement of insider trading regulations. (C) 2012 Elsevier B.V. All rights reserved.
