summary of cash flow
For the year ended December 31,
(in $ millions)
2017
2016
2015
Net cash provided by operating activities
4,563
2,708
2,151
Net cash used in investing activities
(2,830
)
(1,143
)
(2,170
)
Net cash (used in) provided by financing activities
(1,731
)
(2,926
)
395