Waste Connections and Progressive Waste shares fell 5.2% and 7%, respectively; they had fallen further earlier Tuesday but recovered some ground after the companies reaffirmed their commitment. Texas-based Waste Connections Inc. and Toronto-based Progressive Waste Solutions Ltd. agreed in January to merge in an all-stock deal that they expect will close in second quarter. Following the transaction, which is structured as a reverse merger, Waste Connections stockholders will own about 70% of the combined company, and Progressive Waste shareholders will have a 30% stake. Companies often strike inversion merger deals, in which a foreign company buys a U.S. firm and places its headquarters in the foreign country, to help avoid a higher U.S. tax rate.