This is a very interesting thread in working out the best strategy for diversification.
Re the T212 pies is there a fee when you sell a stock or a portion of a stock from your pie?
I invest into about 50 companies each month using Trade Republic - using their "savings plans" investing, some of these go in twice a month, once a month, or every three months. I started off going with companies in the S&P and approximating the amount I would invest in them to the weightings of the S&P, but now I'm playing around with the weightings a bit and I have added some companies in sectors like high speed rail and am on the look out for others.
My 50 or so companies I have invested in are in the following order by value of (fractional) shares bought: Microsoft, Berkshire Hathaway, Apple, Amazon, Alphabet, Nvidia, Meta, Broadcom, JPMorgan Chase, Airbus, Allianz, SLR investment, BMW, Pfizer, AXA, Eli Lilly, Roche Holding, LVMH, Salesforce, Deutsche Telekom, Booking Holdings, Visa, Siemens, TSMC, Hercules Capital, DHL Group, ASML, P&G, AbbVie, Duke Energy, Enel, American Electric Power, Mercedes-Benz, Unilever, BASF, J&J, NextEraEnergy, Adobe, AMD, Verizon, United Health, Orsted, L'Oreal, Netflix, Novo-Nordisk, Heineken, Diageo, Kawasaki Heavy Industries, Construcciones y Auxiliar de Ferrocarriles, Nokia, Hitachi. My holdings values range from 89eur and 74eur for my top two shares, to 1eur each in the last five. My monthy total investment amount is about 140/150, which I may increase as I go along.
Each time I sell a share or portion of, incurs a 1eur fee. I think I will be selling my 5eur or so in United Health in the wake of what just happened with the Luigi thing, I hadn't known too much about the denial of care so it just seems unethical in my book to keep investing in them. I might also down the line get out of a sector, reduce the number of companies, or rejig the weightings further.
So for me, diversification is a multiple of things including different sectors and regions coupled with dollar cost averaging rather than buying all at one time and not knowing if that was too high a price. Previously I invested in two companies in 2018 and 2020 in largely the latter buying strategy and I've suffered quite a devaluation in my share values of these stocks - Nokia, 2018 and Campari, 2020 - and it doesn't seem like they will recover to the initial price with respect to Nokia at all or to anywhere near the high price for Campari any time soon. So I am very wary of going with that type of buying again. I'm in my early 40s so I have 20 to 30 years for my investment portfolio to grow.