I think he started March 14th based on trading volume. Goes from ~15M/day to 35M/day for the next few days before settling down. (Made another comment elsewhere on this)

https://www.sec.gov/Archives/edgar/data/1418091/000110465922...

Ok so assuming march 14 to April 1. The market was up 8% over that time and TWTR was up 19%. Beta is 1.3 so with a beta adjustment the excess return from musk's buying is about 19-(8*1.3)=8.6%.

Is this a lot or a little impact for buying close to 10 percent of a large cap stock? It's hard to say. I'd say it's a bit lower than i would have expected. Nonetheless, it provides somewhat of a floor if musk decides to sell his stake.

Edit: https://www.sec.gov/Archives/edgar/data/0001418091/000110465...

Musk bought between Jan 31 and April 1. Market was up 2.8% and Twitter was up 11.5%. So the impact was less. 7.8% beta adjusted.... Really not much...

Want to write a contract for where it'll be at close of market the first trading day after he announces he'll pull out? We can have break-even at Twitter being 19% down from now. You can appropriately hedge beta risk elsewhere and I'll put in $100 to induce participation. I'd prefer max $10k exposure for my side.

I can meet you in SF if you want signatures.

In the months before Musk started buying, Twitter stocked declined by about 40% while the S&P was up slightly. Is it reasonable to assume that TWTR would have followed the market from Jan 31 to April 1 without Musk?

Good observation. Market impact is notoriously hard to measure - especially over a 2-month period like this one. You have to build a more complex model - which includes fundamentals.