...NEW YORK (S&P Global Ratings) June 5, 2018--S&P Global Ratings today assigned its 'A-' issue-level rating to Union Pacific Corp.'s proposed senior unsecured notes. The company will use the proceeds from this issuance for general corporate purposes, including share repurchases. ISSUE RATINGS--SUBORDINATION RISK ANALYSIS Capital structure + Union Pacific's capital structure consists primarily of senior unsecured debt (not including the proposed notes) and a modest amount of secured debt, most of which was issued at the parent level. As of March 31, 2018, the company had unsecured debt of around $14 billion and secured debt of about $2 billion. Analytical conclusions + We rate Union Pacific's unsecured debt 'A-', the same as our corporate credit rating on the company, because no significant elements of subordination risk are present in its capital structure. RELATED CRITERIA + Criteria - Corporates - General: Reflecting Subordination Risk In Corporate Issue Ratings, March 28, 2018 + General...