Do stock dividends stack?

For the drug pack, do they stack or I have to collect it for me to get another one in 7 days? And what about the stock that gives 100E a week?

All stocks don't stack, they need to collected for the next one to start counting.

I get 2 drug packs and 2 med packs from stocks and they are stacked, so I only have to collect once to get the 2. They can then be opened one at a time.

E and happy stack, edu reduction doesn't. It should tell you if it stacks once you buy the first one.

The 100 e stock stacks as well.

by stack i do'nt mean, buying a second block, I meant not collecting a stock dividend once it is ready

Oh, no. You have to collect it or it just sits there.

If i'm reading the OP correctly. I think he's asking if he can just sit on 100E one week, and collect 200E the next. 

If this is what he means, no, you cannot do that. You have to collect the benefit in order to get the next time period started. 

Not gonna beat a dead horse since it's been answered. But for tactical purposes you can let your MCS stock stay unclaimed in order to position it on the days you typically have RWs unless you prefer to use it for training.

It can be a nice boost for war hits though, I have 400 every Sunday. It sucks letting it go to waste for a week if your original collection day was like Monday, but it makes up for it when you need that clutch E in war. 

Bro, you're almost 2k days. How much did you pay for this account?

MCS stack up to 1000 energy

Sorry, I misunderstood the question. No, stock dividends do not stack over time. It's use them or lose them.

Don't judge me );

You can BUY mcs up to 1000, it doesn't stack up to 1000.

Conversely, is it correct that there are some stocks that you can buy multiple "blocks" of and receive multiple rewards? As a random example, if you could own 2,000,000 shares of whatever stock that will give you two hotel coupons or whatever (1,000,000 shares for each hotel coupon up to a maximum of x)?

Yes.

Anything which gives a payout dividend instead of a passive bonus, you can buy multiple blocks of to get multiple payouts (with each block costing twice as much as the previous one)

If you buy the second block while the first one is midway through the payout countdown, you will get it added to the payout AFTER that one.

The question being asked by OP was "Can I leave these dividends unclaimed, and let them build up" - which is no, the progress to the next payout stops while the dividend is waiting to be claimed.