More to the point, even as the major airlines have been reaping large profits over the last four years, their productivity has not risen at all, suggesting that consolidation is not improving efficiency.
( ( More ( to ( the point ) ) ) ( , ( ( even ( as ( ( the ( major airlines ) ) ( have ( been ( ( reaping ( large profits ) ) ( over ( the ( last ( four years ) ) ) ) ) ) ) ) ) ) ( , ( ( their productivity ) ( ( ( has not ) ( ( ( risen ( at all ) ) , ) ( suggesting ( that ( consolidation ( ( is not ) ( improving efficiency ) ) ) ) ) ) ) . ) ) ) ) ) )
(ROOT (S (ADVP (RBR More) (PP (TO to) (NP (DT the) (NN point)))) (, ,) (SBAR (RB even) (IN as) (S (NP (DT the) (JJ major) (NNS airlines)) (VP (VBP have) (VP (VBN been) (VP (VBG reaping) (NP (JJ large) (NNS profits)) (PP (IN over) (NP (DT the) (JJ last) (CD four) (NNS years)))))))) (, ,) (NP (PRP$ their) (NN productivity)) (VP (VBZ has) (RB not) (VP (VBN risen) (ADVP (IN at) (DT all)) (, ,) (S (VP (VBG suggesting) (SBAR (IN that) (S (NP (NN consolidation)) (VP (VBZ is) (RB not) (VP (VBG improving) (NP (NN efficiency)))))))))) (. .)))
Airlines don't produce much profit but have become highly productive. 
( Airlines ( ( ( ( ( do n't ) ( produce ( much profit ) ) ) but ) ( have ( become ( highly productive ) ) ) ) . ) )
(ROOT (S (NP (NNPS Airlines)) (VP (VP (VBP do) (RB n't) (VP (VB produce) (NP (JJ much) (NN profit)))) (CC but) (VP (VBP have) (VP (VBN become) (S (ADJP (RB highly) (JJ productive)))))) (. .)))