def odds_ratio(target_a, target_c, peer_b, peer_d):
    portfolio_x = float(target_a) / float(target_a + target_c)
    portfolio_y = float(peer_b) / float(peer_b + peer_d)

    odds_numer = portfolio_x / (1.0 - portfolio_x)
    odds_denom = portfolio_y / (1.0 - portfolio_y)

    return int(odds_numer / odds_denom)