BALTIMORE (Stockpickr) -- Forget about sales and profitability numbers for a second this earnings season because there's an even more important number that stocks are reporting this summer: cash.

Cash is key because, unlike earnings, it's not subject to one-time events or GAAP accounting trickery. Instead, what you see is pretty much what you get.

More important, at a time when the big market indices are hovering around all-time highs and anxiety is ramping up among investors, cash provides what amounts to a very real discount on a stock's share price. Cash also provides options. Firms with cash can opt to increase shareholder value by paying a dividend or initiating a share buyback. Plus, they have the ability to take advantage of pricey M&A opportunities and internal investments.

The good news is that there's no shortage of cash in the marketplace today. Companies in the S&P 500 currently hold approximately $1.75 trillion in cash and marketable securities, the highest cash cushion in corporate history. Ironically, the most cash-rich stocks also tend to trade at a discount for holding big net cash balances on their balance sheets. But with the possibility of an interest rate hike from the Fed later this year, that huge cash reserve could soon look at lot more valuable to investors who buy today.

To find some attractive investment opportunities in these cash-rich stocks, we're taking a closer look at five of them today.

Apple


We've got to start things off with Apple  (AAPL - Get Report). Apple currently holds more cash than any other company. In fact, during the firm's third-quarter earnings call earlier this month, it announced that its cash pile had actually crossed the $200 billion mark, the first company ever to cross that threshold.

While that number understandably grabbed the headlines, it's actually not the most important cash measure to look at in Apple. Instead, that's net cash, which measures how much dry powder Apple has left over when you take out all of its debt. With $129 billion in net cash, Apple could still afford to pay for more than 18% of its current market capitalization today.

That's a huge discount on a stock that already trades for less than 15 times trailing earnings.

Apple's cash generation has a lot to do with the fact that the firm is one of the most profitable names in the electronics business. The firm's integrated hardware and software offerings in the Macintosh computer line and iPhone and iPad portables mean that Apple is able to collect dramatically thicker margins than its less-entrenched rivals. That's because Apple can squeeze more performance out of less pricey hardware specs through optimization.

The Apple ecosystem also provides a sticky customer base. High levels of interoperability between devices and sunk costs in app purchases help to encourage loyalty.

One of the interesting things about Apple's huge net cash cushion is the fact that it's not just hoarding cash here. The firm has actually been actively returning cash to shareholders in the form of dividends and share buybacks.

Wall Street reacted poorly to an overall bullish earnings call last week -- and that presents a buying opportunity for investors this summer.

Qualcomm


Qualcomm  (QCOM - Get Report) is another cash-rich stock from the tech sector. This mobile chipmaker is currently sitting on nearly $13 billion in net cash and investments, enough to pay for 13% of its market capitalization at current price levels.

While shares don't trade for quite the bargain price tag seen in Apple, Qualcomm still trades for approximately 17 times earnings right now. That's far from a frothy valuation in this market.

If there's a smartphone in your pocket, there's a good chance you paid Qualcomm for the privilege of owning it. That's because the firm is the world's biggest wireless chipmaker, providing processors and communication chips for a large number of mobile phones.

Even if your phone doesn't have Qualcomm hardware, though, the firm still likely collected a royalty on it. Qualcomm is also a major patent licensor, collecting royalties for effectively every 3G and 4G LTE handset that rolls off an assembly line today.

With short replacement cycles in the mobile handset business, the high churn of devices has provided a big tailwind for Qualcomm. That's not likely to abate, even if a recent antitrust investigation in China ate about $975 million in fines.

There's still plenty of cash left over for shareholders -- and with a hefty 3% dividend yield at current price levels, it's being returned to them at a fast pace.

While shares have been under pressure for much of 2015, shares are starting to look "bottomy" again. A breakout above $65 is a technical buy signal in this cash-rich stock.

Priceline Group


Online travel giant Priceline Group  (PCLN) has been experiencing rapid growth in recent years, rallying as it unlocked big, untapped travel markets in regions such as Europe, Latin America and Asia. The firm provides bookings for hotels, restaurants, airline tickets, car rental, cruises and other vacation packages, earning profits through its transaction fees. Besides new markets, Priceline has bought its way into growth through high-profile acquisitions of companies like Kayak and OpenTable.

Priceline is essentially a middleman between travel service providers and consumers. For instance, if a hotelier has unsold inventory, it can turn to Priceline to fill its rooms at discount prices. Because travel typically has very low variable costs, selling unsold rooms and airplane seats is a huge value-add for providers -- and Priceline's big network makes it an equally popular draw for consumers looking for good deals.

For markets where travel has become increasingly commoditized (like here at home), more value-added content, like that found on its Kayak subsidiary, should help cement the firm's leadership position.

From a financial standpoint, Priceline is in excellent shape. The firm currently carries $2.9 billion in net cash and investments, enough to pay for about 5% of the firm's current market valuation. 

Priceline's stock momentum may have slowed a bit in 2015, but it's still alive here, and shares are within grabbing distance of year-to-date highs this month.

Investors get their next cash update from Priceline when the firm reports earnings on Aug. 5.

EMC


EMC  (EMC) has its grips on some of the hottest buzzwords in the IT business right now: cloud computing, Big Data and enterprise storage. Among other things, the firm develops and sells the software and hardware used to link storage devices together in the datacenter and in the cloud. That means that as demand for data storage continues to go parabolic, demand for EMC's services should continue to exhibit stair-step growth.

EMC's cash and investments position currently sits at $5.42 billion, which adds up to more than 10% of the firm's current valuation in the market. That's not all cold, hard cash, though. More than half comes from the firm's majority ownership stake in virtualization company VMWare  (VMW). That VMWare position adds an exposure boost to consumer and small-business customers on EMC's income-statement side.

Like a couple of the other stocks on our list of cash-rich companies, EMC is starting to show signs of life after underperforming at the start of 2015.

For this big data stock, the technical buy signal comes on a push through prior highs at $27.50.

Phillips 66


Last up on our list of cash-rich companies is Phillips 66  (PSX - Get Report).

Despite the fact that Phillips 66 is a stock in the energy sector, shares have actually managed to outperform the S&P 500 pretty handily in 2015. Year-to-date, this $41.6 billion midstream energy stock is up about 10%. That's double the performance of the S&P 500 over that same stretch.

Phillips 66 spun off from ConocoPhillips  (COP) a few years back, a move that distanced the company from the recent crash in energy prices. Today, Phillips 66 owns 15 refineries around the world that have the capacity to process more than 2.4 million barrels of crude oil per day. Phillips 66 also owns a commodity transportation business with about 62,000 miles of pipeline, and a chemical joint venture that makes petrochemicals and plastics.

Like other midstream energy stocks, this company pays a solid dividend yield (just shy of 3% as I write), and it's got plenty of cash to keep paying it. All told, Phillips 66 has nearly $7 billion in net cash and investments -- enough to pay for about 16.5% of its current shares outstanding.

Between the firm's upward trajectory and its bargain price tag, shares look attractive at current levels. Just look out for earnings risk on the horizon on July 31.

This article is commentary by an independent contributor. At the time of publication, the author was long Apple.