Marc Casper, President & Chief Executive Officer of Thermo Fisher Scientific, Inc. (NYSE:TMO) in the fourth quarter earnings call replied on the inquiry regarding future acquisitions, "In terms of the target leverage ratios, we like to operate day-to-day in the 2.5 to 3 times. We're willing to spike up to about 4.5 times so we have plenty of capacity at any point in time if we want to deploy capital on something that clearly create shareholder value. And occasionally, those larger opportunities present themselves but I think you should expect us to be doing bolt-on acquisitions as based on where the number of companies really are in terms of opportunities".