Ann: Becoming a substantial holder, page-17

Base1864
A swap is simply an agreement to swap one asset for another at some time in the future - as such, it is a type of derivative.
Here, it seems that Athos and MS have been agreeing to swap TPD stock back and forth between themselves with the purpose of accumulating.
But I cannot be sure what is going on, exactly, without knowing the exact nature of the agreements made between Athos and MS. There could be all sorts of conditions attached to the swaps before they are actually executed.
But it seems to me like Athos and MS have been working together to acquire stock, with Athos, the hedge fund, running the bot side of things.
In doing so, they have created a mechanism in which two-related parties can acquire stock under the radar by hiding behind nominee accounts and avoiding scrutiny under the 5% rule.
This, of course, flies pretty close to the sun in terms of declaring beneficial ownership (i.e. if the stock acquired by Athos was always intended for MS then MS are the beneficial owner).
But I saw something very similar with the Ambassador Oil takeover years ago, where some random hedge fund suddenly turned up with a substantial holding and then sold to Drillsearch immediately when they announced their takeover (which led to a court case).

Another interesting piece of information in this announcement is that Athos was buying swaps off MS up until the day before MS declared their substantial interest notice (24/10). This suggest they were both buying, but MS were offloading their holdings via swaps to delay breaching the 5% rule. When MS declared its 5% holding, the buying of swaps miraculously stopped.
Then, on the 15th of November, they sold swaps back to MS. So, depending on whether MS executes this swap, you might expect another large change in MS's substantial holding in the following days. As we are coming to voting time, MS (or whoever they are representing) will need to show their hand if the plan is to negotiate with STX for a better deal. Then again, they may simply be planning to convert.

I have to admit, while I have a decent education in this area, I have little practical experience in derivative trading, especially when it comes to 'gaming' beneficial ownership rules, so happy for someone to provide a better or alternative explanation.