We examine the effect of corporate spinoffs on the trading environment of the stock of firms that spinoff units. Spinoffs change the information environment of firms. The increased transparency following spinoffs can obviate informed traders' information or make it more valuable. We find that residual return variance increases following spinoffs. More importantly, transaction costs and the price impact of trades are also higher following spinoffs. These results are stronger for spinoffs where parent firms divest unrelated subsidiaries. Changes in the information environment associated with focusing spinoffs appear to benefit informed traders at the expense of uninformed traders.