Is Rambus a Bargain?

Numbers can lie -- but they're the best first step in determining whether a stock is a buy. In this series, we use some carefully chosen metrics to size up a stock's true value based on the following clues:

• The current price multiples.
• The consistency of past earnings and cash flow.
• How much growth we can expect.

Let's see what those numbers can tell us about how cheap Rambus (Nasdaq: RMBS), the holder of many valuable memory patents, might be.

The current price multiples
First, we'll look at most investors' favorite metric: the P/E ratio. It divides the company's share price by its earnings per share -- the lower, the better.

Then, we'll take things up a notch with a more advanced metric: enterprise value to unlevered free cash flow. This divides the company's enterprise value (basically, its market cap plus its debt, minus its cash) by its unlevered free cash flow (its free cash flow, adding back the interest payments on its debt). Like the P/E, the lower this number is, the better.

Analysts argue about which is more important -- earnings or cash flow. Who cares? A good buy ideally has low multiples on both.

Rambus has a P/E ratio of 25.5 and an EV/FCF ratio of 10.5 over the trailing 12 months. If we stretch and compare current valuations to the five-year averages for earnings and free cash flow, Rambus has a negative P/E ratio and a five-year EV/FCF ratio of 52.8.

A one-year ratio under 10 for both metrics is ideal. For a five-year metric, under 20 is ideal.

Rambus is 0 for 4 on hitting the ideal targets, but let's see how it compares against some competitors and industry mates who also rely on valuable IP in the semiconductor industry. 

Source: Capital IQ, a division of Standard & Poor's; NM = not meaningful.

Numerically, we've seen how Rambus' valuation rates on both an absolute and relative basis. Next, let's examine ...

The consistency of past earnings and cash flow
An ideal company will be consistently strong in its earnings and cash flow generation.

In the past five years, Rambus' net income margin has ranged from -110.2% to 33.8%. In that same time frame, unlevered free cash flow margin has ranged from -26.5% to 64.1%.

How do those figures compare with those of the company's peers? See for yourself:

Source: Capital IQ, a division of Standard & Poor's; margin ranges are combined.

Additionally, over the last five years, Rambus has tallied up two years of positive earnings and three years of positive free cash flow.

Next, let's figure out ...

How much growth we can expect
Analysts tend to comically overstate their five-year growth estimates. If you accept them at face value, you will overpay for stocks. But while you should definitely take the analysts' prognostications with a grain of salt, they can still provide a useful starting point when compared to similar numbers from a company's closest rivals.

Let's start by seeing what this company's done over the past five years. In that time period, Rambus has put up past EPS growth rates of 36.4%. Meanwhile, Wall Street's analysts expect future growth rates of 47%.

Here's how Rambus compares it its peers for trailing five-year growth:

Source: Capital IQ, a division of Standard & Poor's; EPS growth shown. Synopsys' growth rate is zero because of negative earnings five years ago that do not give a meaningful value.

And here's how it measures up with regard to the growth analysts expect over the next five years:

Source: Capital IQ, a division of Standard & Poor's; estimates for EPS growth. Alternate data from Yahoo! Finance lists Rambus' growth rate at 10%.

The bottom line
The pile of numbers we've plowed through has shown us how cheap shares of Rambus are trading, how consistent its performance has been, and what kind of growth profile it has -- both on an absolute and a relative basis.

The more consistent a company's performance has been and the more growth we can expect, the more we should be willing to pay. We've gone well beyond looking at a 25.5 P/E ratio.

One caveat ... Rambus' estimated five-year growth using our data provider is only from one analyst. Looking at Yahoo! Finance for a second opinion, analysts estimate 10% growth going forward. That sounds more reasonable.

If you find Rambus' numbers compelling, don't stop. Continue your due diligence process until you're confident the initial numbers aren't lying to you.

Click here to add Rambus to My Watchlist to find all of our Foolish analysis on this stock.