We've been on quite a long bull market for equities, and with oil prices rising and unemployment still at pesky levels, a bull market can turn bear at a moment's notice. So how can we protect ourselves and sleep at night with questions surrounding the economy?

You may sleep well stuffing your extra cash under your mattress, but over time that's bound to lead to back problems. So why not invest in companies that have cash burning a hole in their pockets and businesses that spit off more cash faster than they can spend it? Not only does cash provide a safety net when and if the stock market takes another tumble, it can also be ammunition for future growth.

Here are four tech companies with not only dominant market positions but also lots of cash that should help any investor sleep at night.

Company

Market Cap

Net Cash and Short-Term Investments

2010 Operating Cash Flow

Apple (Nasdaq: AAPL)

$324.1 billion

$27.0 billion

$22.6 billion

Microsoft (Nasdaq: MSFT)

$217.4 billion

$30.3 billion

$25.4 billion

Intel (Nasdaq: INTC)

$115.2 billion

$19.8 billion

$16.7 billion

Cisco (Nasdaq: CSCO)

$99.9 billion

$25.0 billion

$10.5 billion

Source: Yahoo! Finance. Cash and short-term investment figures are net of long-term debt.

Apple and Microsoft dominate our computer landscape, and with operating cash flowing in as if Hoover Dam had busted wide open, they have plenty of cash for further investment. Similarly, Cisco has a strong position in networking. And while Intel is in a somewhat more capital-intensive business, this only helps bolster its barrier to entry for competitors. All four of these companies are therefore free to invest in research, acquisitions, or in Apple's case, Treasuries.

A competitive moat and cash is a wonderful thing, and all of these companies have both.

Getting some Zzzz's
There's lots of cash sitting on the sidelines right now, especially in tech, but that can create a nice cushion for investors. Cash can help your portfolio, whether we go through more economic turbulence or if companies put it to work for growth. Berkshire Hathaway's (NYSE: BRK-A) (NYSE: BRK-B) famous cash hog, Warren Buffett, has even said his "elephant gun has been reloaded" and that if a good deal comes along, he may jump on it.

So what investments help you sleep at night? Leave your thoughts in the comments section below.

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