A disclaimer: I am an engineer, not an accountant. I feel confident speaking on the top-level economics of the topic, but am not reliable on the hard-core finance tools (heges, futures, derivatives, etc). I am not publishing this as a guide, but instead discussing my opinions on applying the topics to your own EVE experiences... Use with caution, regard with a grain of salt.
Real Life Analogs
Stockpiling, or hedging, allows for insuring against future price spikes. Airline fuel is the common example: if I expect prices to be higher in the fall, I will hedge against that price and find a way to lock in a lower price in advance of that spike.
Since EVE lacks the nuances of modern financial products, hedging is done by stockpiling. Whether that is hoarding products for price spikes, or just keeping a backlog of raw materials to quickly react to price sways in manufactured product.
In EVE, I don't dare, for one second, to claim I know how to read the commodity markets. In the traditional sense of hedges to "insulate against price spikes" I am a miserable failure. Instead, let's look at the different ways we can stockpile to make the industrial process less painful.
The cost of stockpiling is ISK. ISK that can't be used for other processes, ISK that isn't being turned into more ISK, ISK that can be stolen/lost/depreciate. It's very easy to have a project that has more value in stockpiled goods than actual net products. This is the reason I treat stockpiling so gingerly.
Since the goals should be to simplify the industrial process (hauling, building), and try to make more ISK, pick your stockpile carefully. Having large stores of commodities like Tritanium might make heavy production more agile. Holding back product for the swings of market ups-and-downs might mean more ISK/unit. Having a store of built T2 components might better utilize build times. Just remember, that's ISK not in the wallet. Also, the further refined the product is, the harder it is to cash-out the stockpile if something goes wrong.
Raw Material Stockpiles
Personally, I am a big advocate of stockpiling low-end minerals, and high-volume PI materials. I should hold on to more moon components and T1, but I find those products are either light enough to transport easily or have such a small price differential, they aren't worth holding on to.
A practice I am trying to get better at is becoming smarter at stockpiling things that are essentially free (blue print copies), or take very little liquid ISK to hold on to (datacores/decryptors). Stockpiling these intermediates serves to make the T2 manufacturing process much more agile. Even T2 BPCs are pretty cheap to hold on to. Also, they may be a theft risk because of : shiny: but would be such a pain to monetize, I can't imagine someone having the patience required.
Since I am so bad at extrapolating trends, and tend to try and keep all my ISK working at all times, I don't like stockpiling finished product. But, for the supply-oriented manufacturer, holding the same margin as the expected profit is like holding free goods. This can be useful to portion off 10-30% of products for going straight into corp use.
My problem with corp-use product stockpiles was two fold. On the one hand, managing getting product into the hands of members is a pain. On the other hand, keeping a diverse enough stockpile is a massive headache. Why do we have one gun but not another? Why can't I have the whole ship comped? Trying to balance both an ISK-generating manufacturing house AND a direct PVP supplier is a lot of headache.
Cash is king. Unlike the other stockpiles, cash can be turned directly into product instantly. Whether that's ship equipment for the corp, or materials for manufacturing. Though some will argue it's not the most efficient to just sell-order 100% of your materials, or buy-order 100% of your products, there's nothing like having piles of cash to just get it done.
Personally, this is the means I like to stockpile. Unfortunately, as I mentioned earlier, I have a personal bad habit to invest stockpiles too readily and end up over leveraged. Also, cash is really easy to move and steal. So be careful how you hold cash.
Security and Stockpiles
As countless corp thefts have highlighted, a stockpile is a target just like any PVP engagement. Any pile of goods can be stolen by anyone. Some thoughts to keep in mind:
- Difficulty of monetization: Good stockpiles are hard turn into cash
- Enormous piles of trit are heavy to transport
- T2 BPCs take a lot of time and/or material to manufacture
- Intermediaries might not have a player market (T1, RAM)
- Security of materials: Corp tools are your friends
- Secure hangers by need of access
- Utilize POS lab use/take rules to protect materials
- Alt stashing cash
- Remember: nothing is 100% secure once you involve human interaction
- Utility of stockpile
- Don't be afraid to reduce stocks if inputs > utilization
- No reason stockpiles can't be fluid. Change to suit needs