Now witness the power of this fully operational online broker account
For most people (US citizens see the note at the end of this post), the best option for opening investment accounts is going to be online. Banks and full service broker offices tend to have higher fees, more limited product availability, and lots of pushy salespeople who would be delighted to steer you to expensive and profitable (for them) options.
Finally I got around to opening an account at each of the three big online brokers: Rakuten, SBI, and Monex. Been meaning to do so for a while now, mainly in order to be able to log in and look at the interfaces so we can help people navigate them.
Originally I had my taxable account, NISA account, and iDeCo account at Rakuten, along with my wife's taxable account and NISA account.
While it is convenient to have all your accounts with the same company (you only have to remember one login and learn one interface), there is a tiny amount of institutional risk. Your account could be hacked or the broker could run into technical or financial difficulties.
The actual chances of something bad happening to an account at one of the big three is probably miniscule, but I am a strange person who feels better when small esoteric risks have been considered and dealt with.
Accordingly I now have a taxable account at Monex and my wife's iDeCo account is going to move to SBI (from Iwate Bank, which used to be a competitive provider but no longer is). We're also considering moving some of my wife's investing to SBI from Rakuten.
My first impression is that all three companies are pretty similar. They all offer domestic stocks, ETFs and mutual funds, US stocks and ETFs, and a bunch of other services I am not interested in (frequent trading, FX, margin trading, futures, etc.).
They all offer iDeCo and all three types of NISA accounts. They all offer reporting taxable accounts (that calculate and pay your taxes for you).
I think Monex has more stocks available, SBI has more funds available in its iDeCo account, and I am not sure what Rakutes is good at (but I've been fairly happy with them so far).
* US citizens may have trouble opening and using investment accounts in Japan (due to US regulations and reporting requirements). There are also some types of investments (foreign domiciled mutual funds, etc.) that might be best avoided because of the way the IRS treats them. For these reasons many Americans prefer to invest in existing accounts in the US or open an account with Interactive Brokers. American Citizens Abroad is a group that shares information and lobbies to change US tax laws on expats.
We're planning to make some simple user guides to the big three sometime soon. Please post any questions in the comments!