Based on your financial expertise, provide your response or viewpoint on the given financial question or topic. The response format is open.

Stock trading models that use fundamental analysis, e.g. PEG ratios?
Maria, there are a few questions I think you must consider when considering this problem. Do fundamental or technical strategies provide meaningful information? Are the signals they produce actionable? In my experience, and many quantitative traders will probably say similar things, technical analysis is unlikely to provide anything meaningful. Of course you may find phenomena when looking back on data and a particular indicator, but this is often after the fact. One cannot action-ably trade these observations. On the other hand, it does seem that fundamentals can play a crucial role in the overall (typically long run) dynamics of stock movement. Here are two examples, Technical: suppose we follow stock X and buy every time the price crosses above the 30 day moving average. There is one obvious issue with this strategy - why does this signal have significance? If the method is designed arbitrarily then the answer is that it does not have significance. Moreover, much of the research supports that stocks move close to a geometric brownian motion with jumps. This supports the implication that the system is meaningless - if the probability of up or down is always close to 50/50 then why would an average based on the price be predictive? Fundamental: Suppose we buy stocks with the best P/E ratios (defined by some cutoff). This makes sense from a logical perspective and may have some long run merit. However, there is always a chance that an internal blowup or some macro event creates a large loss.  A blended approach: for sake of balance perhaps we consider fundamentals as a good long-term indication of growth (what quants might call drift). We then restrict ourselves to equities in a particular index - say the S&P500. We compare the growth of these stocks vs. their P/E ratios and possibly do some regression. A natural strategy would be to sell those which have exceeded the expected return given the P/E ratio and buy those which have underperformed. Since all equities we are considering are in the same index, they are most likely somewhat correlated (especially when traded in baskets). If we sell 10 equities that are deemed "too high" and buy 10 which are "too low" we will be taking a neutral position and betting on convergence of the spread to the market average growth. We have this constructed a hedged position using a fundamental metric (and some helpful statistics). This method can be categorized as a type of index arbitrage and is done (roughly) in a similar fashion. If you dig through some data (yahoo finance is great) over the past 5 years on just the S&P500 I'm sure you'll find plenty of signals (and perhaps profitable if you calibrate with specific numbers). Sorry for the long and rambling style but I wanted to hit a few key points and show a clever methods of using fundamentals.