I am a quantitative finance student, and during the first year of this Master’s Degree I couldn’t help but notice that there’s a lot of focus on derivatives pricing and little or none on stock pricing. Shouldn’t stock pricing be important, for example to help determine a fair value?
I think the comment provided by nbbo2 answers your question fairly well and is pointing in the right direction. To make the answer more concrete, it's important to note that unlike with other types of assets, derivative prices in the Black-Scholes world are driven mainly by changes in the price of the underlying. This means that the randomness of the underlying asset (described by the typical Brownian motion term) drives both the price changes in the asset itself and in the derivative price. This means that by choosing a portfolio with right weightings of the underlying and of the derivative (go long in the derivative and short in the underlying) you can cancel out the source of randomness (the Brownian motion term) and completely hedge your position.
Pricing equity assets, on the other hand, is much more difficult because, as mentioned by nbbo2, the price depends on a lot of different factors, which means that the models are bound to be less precise (DCF, DDM, etc.).