Table:
|  | July 27, 2019 | July 28, 2018 | Increase (Decrease) |
| --- | --- | --- | --- |
| Cash and cash equivalents . | $11,750 | $8,934 | $2,816 |
| Available-for-sale debt investments | 21,660 | 37,009 | (15,349) |
| Marketable equity securities | 3 | 605 | (602) |
| Total | $33,413 | $46,548 | $(13,135) |
Paragraphs:
Balance Sheet and Cash Flows
Cash and Cash Equivalents and Investments The following table summarizes our cash and cash equivalents and investments (in millions):
The net decrease in cash and cash equivalents and investments from fiscal 2018 to fiscal 2019 was primarily driven by cash returned to shareholders in the form of repurchases of common stock of $20.7 billion under the stock repurchase program and cash dividends of $6.0 billion, net cash paid for acquisitions and divestitures of $2.2 billion, a net decrease in debt of $1.1 billion, and capital expenditures of $0.9 billion. These uses of cash were partially offset by cash provided by operating activities of $15.8 billion and the timing of settlements of investments and other of $2.0 billion.
In addition to cash requirements in the normal course of business, on July 9, 2019 we announced our intent to acquire Acacia Communications, Inc. (“Acacia”) for a purchase consideration of approximately $2.6 billion in cash. Additionally, $0.7 billion of the U.S. transition tax on accumulated earnings for foreign subsidiaries, $6.0 billion of long-term debt and $4.2 billion of commercial paper notes outstanding at July 27, 2019, are payable within the next 12 months from the balance sheet date. See further discussion of liquidity and future payments under “Contractual Obligations” and “Liquidity and Capital Resource Requirements” below.
We maintain an investment portfolio of various holdings, types, and maturities. We classify our investments as short-term investments based on their nature and their availability for use in current operations. We believe the overall credit quality of our portfolio is strong, with our cash equivalents and our available-for-sale debt investment portfolio consisting primarily of high quality investment-grade securities. We believe that our strong cash and cash equivalents and investments position allows us to use our cash resources for strategic investments to gain access to new technologies, for acquisitions, for customer financing activities, for working capital needs, and for the repurchase of shares of common stock and payment of dividends as discussed below.
Question:
How are the company's investments classified as short-term?
Answer: based on their nature and their availability for use in current operations.