Halliburton 

Halliburton is North America's largest oilfield-services company as measured by market share. Despite industry fragmentation, it holds a leading position in the hydraulic fracturing and completions market, which makes up nearly half of its revenue. It also holds strong positions in other service offerings like drilling and completions fluids, which leverages its expertise in material science, as well as the directional drilling market. While we consider SLB the global leader in reservoir evaluation, we think Halliburton leads in any activity from the reservoir to the wellbore. Halliburton's innovations have helped multiple producers lower their development costs per barrel of oil equivalent, with techniques that have been honed over a century of operations.