Raise your hand if you've ever gotten a "hot stock tip."

Keep it raised if the tip came out of the blue, from someone you've never met, in the form of an email in your inbox.

Yeah. That's what I thought. And I hope you're as skeptical of these things as I am (how skeptical am I? Let's jut say that the letters "ele" are looking pretty worn on my delete key.) Yet on Friday, I got just such a tip -- but I didn't delete the email. Why? Because as the Dow was taking its biggest one-day plunge of the year, this particular "tipped" stock swam above the tide to close up 15%. Moreover, this price spike couldn't have been the kind you see in hyped penny stocks, because the stock in question -- investor educator/broker Investools (NASDAQ:SWIM) -- is just too big to hype. As in, $800 million market cap big.

And so, I took a closer look. Here's what I found.

The skinny on Investools
In case you haven't heard of this firm (and I knew it by name only until last week), let's begin with a brief outline. Investools operates essentially two businesses. Its education segment offers investors courses, workshops, and even one-on-one coaching in stock investing, options trading, and related subjects. Students partaking of Investools' educational offerings are then fed into the firm's other business operation, online trading, making each customer a potential source of two revenue streams.

The company booked only its fifth-ever profitable quarter in the second quarter (the last one was in 2005), with a tiny $0.05-per-share net profit. But this firm -- like several others we cover at Motley Fool Hidden Gems, including active recommendation Blackboard (NASDAQ:BBBB), and "Tiny Gem" Natus Medical (NASDAQ:BABY), or like Symantec (NASDAQ:SYMC), recommended by our esteemed colleagues at Motley Fool Inside Value -- is currently working through the accounting effects of a major acquisition: its September 2006 purchase of thinkorswim. As the GAAP accounting rules require the now-combined firm to write down the value of its acquisition, the true cash profitability of the whole is currently being obscured.

For example, in Q2, Investools earned only $3.7 million, right? But that's only under GAAP. Fact of the matter is, when you tally up the cash profits, Investools generated more than twice that amount in free cash flow -- $8.6 million to be exact -- as new accounts tripled versus last year, and revenue at the brokerage arm surged 83%.

Now, I'm just about out of space in this column, so I'll pause on the analysis right here. But rest assured that in quarters to come, we'll be looking at Investools in more depth. In the meantime, I'd urge you to practice restraint -- don't rush out and buy this stock without doing your own due diligence first.

Meanwhile, if you're looking for an online stock trader whose business we have already fully vetted and found superb, we have one of those ready for you right now. Take a free trial of Motley Fool Stock Advisor, and find out who we like.

Fool contributor Rich Smith does not own shares of any company named above. The Fool has a disclosure policy.