agreements, and our co-branded credit card agreements, offset by cash payments we make for products and services, employee compensation (less amounts capitalized related to internal-use software that are reflected as cash used in investing activities), payment processing and related transaction costs, operating leases, and interest payments on our long-term obligations. Cash received from our customers and other activities generally corresponds to our net sales. Because consumers primarily use credit cards to buy from us, our receivables from consumers settle quickly. The increase in operating cash flow in 2015 , compared to the comparable prior year period, was primarily due to the increase in net income (loss), excluding non-cash charges to net income (loss) such as depreciation, amortization, and stock-based compensation, and changes in working capital. The increase in operating cash flow in 2014 , compared to the comparable prior year period, was primarily due to the increase in non- cash charges to net income (loss), including depreciation, amortization, and stock-based compensation, partially offset by changes in working capital. 

Cash provided by (used in) investing activities corresponds with cash capital expenditures, including leasehold improvements, internal-use software and website development costs, cash outlays for acquisitions, investments in other companies and intellectual property rights, and purchases, sales, and maturities of marketable securities. Cash provided by (used in) investing activities was $(6.5) billion , $(5.1) billion , and $(4.3) billion in 2015 , 2014 , and 2013 , with the variability caused primarily by our decision to purchase or lease property and equipment, purchases, maturities, and sales of marketable securities, and changes in cash paid for acquisitions. Cash capital expenditures were $4.6 billion , $ 4.9 billion , and $ 3.4 billion in 2015 , 2014 , and 2013 . This primarily reflects additional investments in support of continued business growth due to investments in technology infrastructure (the majority of which is to support AWS), and additional capacity to support our fulfillment operations, during all three periods. Capital expenditures included $528 million, $537 million, and $493 million for internal-use software and website development in 2015 , 2014 , and 2013 . Stock-based compensation capitalized for internal-use software and website development costs does not affect cash flows. In 2015 , 2014 , and 2013 , we made cash payments, net of acquired cash, related to acquisition and other investment activity of $795 million , $979 million , and $312 million . 

Cash provided by (used in) financing activities was $(3.8) billion , $4.4 billion , and $(539) million in 2015 , 2014 , and 2013 . Cash outflows from financing activities result from principal repayments on obligations related to capital leases and finance leases and repayments of long-term debt and other. Principal repayments on obligations related to capital leases and finance leases and repayments of long-term debt and other were $4.2 billion , $1.9 billion , and $1.0 billion in 2015 , 2014 , and 2013 . The increase in 2015 primarily