I pretty much only invest/trade companies that are being re-rated or have a high potential of re-rating.
IMO The underlying drivers of re-ratings come from the fundamentals of a company. There's two key components to this; "Risk" and "Time".
As more news about a company comes to light it typically reduces the risk of the investment by increasing the likelihood of the re-rating fundamental event to occur (ie: contract signing, technology being proven, oil/gas found in well etc.) As the risk reduces the market is more confident to re-rate the company towards its intrinsic value.
Some news can be well known however the re-rating event won't occur for another 2-5 years. Accordingly the time/value of money will come into play, the potential of another GFC, the company may need to raise further cash etc. etc. so all of those things mean the company doesn't jump straight to the re-rated price. There is a "time risk" involved where things can still go wrong.
There's also a third component (not fundamental) and that's market awareness. If no-one is following or knows about a company then it is unlikely to get re-rated. Despite what some claim the markets are not efficient and good stocks take a while for enough people with enough $$$ to notice them. This is where the tech. analysts tend to jump on the bandwagon.
It's my belief that the secret to extra-ordinary returns is identifying companies that:
- Have not been correctly risk adjusted by the market
- Have a very high re-rating potential in the near term
- Doesn't have much market awareness (small/mid caps, little chatter on forums etc.)
I have typically found that as the risk decreases the market awareness tends to increase (although not always, they're the best opportunities), but can be sluggish. This gives an ideal time to "load up" and enjoy the ride as others "discover" the hidden value in the company.
So, to answer your question "How quickly should this happen?"... well it depends. An Oil & Gas company may re-rate in a single day because of results from a single drill hole. A technology company may slowly be re-rated over a couple of years as independent analysis of the technology is verified, the technology is proven on a large scale, a commercialisation partner is secured, funding is secured for expansion etc. etc.
Each company is different and the challenge is to have an in depth level of knowledge of your company. This allows you to identify the "re-rating price drivers" of the company and get an idea of the key milestones and the time it will take for these to occur.
Hope that helped somewhat... but it's just my opinion of course