Which of the following could qualify as a cash flow for the proprietary fund statement of cash flows?

In the context of a proprietary fund statement of cash flows, each item listed can indeed qualify as a cash flow.

The issuance of a check or warrant represents an outflow of cash. This is a direct transaction where cash is disbursed to fulfill liabilities or operational needs, thereby directly impacting the cash flow statement.

The creation or increase of a negative position in pooled cash indicates that the fund has a need to borrow against its cash resources, which can be considered a cash flow event. If the fund is utilizing pooled cash (from a central bank account shared among different funds) and increases its negative position, it reveals changes in cash availability and utilization.

Changes in the fair value of investments are also relevant. Though they do not directly affect cash flows immediately, they reflect fluctuations in asset value that could lead to future cash flows when the investments are sold or otherwise realized. Provisions in accounting standards may allow for such changes to be noted as non-cash investing or financing activities, even though they affect the portfolio's overall health and potential cash flow in future reporting periods.

Therefore, since each item can affect the cash flow statement relevant to proprietary funds, acknowledging all these aspects leads to the conclusion that all listed activities qualify as cash flows.