Buy monthly or bi-monthly VT on IB?


I currently buy CHF 10k worth of VT on IB every two months instead of 5k every month in order to save on the IB currency exchange fee of around CHF 1.80 (USD 2.00 if I remember correctly) for the exchange of my CHF to USD.

Now I was wondering if there is any advantage, even if small, in saving some money/fees if I chose another option such as:

a) buy every month 5k of VT
b) buy every 3 month (quarter) 15k of VT

So to resume my question in another way: would I earn more by immediately placing my money into VT every month (and not save on the currency exchange fee) or better save on the currency exchange fee and place my money bi-monthly or even quarterly?


Time in the market is what matters. IB fees are minimal.

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Pretty simple math.
For purchase of 60000 / year.
Monthly schedule costs you 24USD of fees.
Turns to 0.0004, i.e. 0.04% / year.

With a bi-monthly you then save 0.02%, with a quarterly 0.03%.

I would say irrelevant, because you (and nobody else) don’t know the opportunity costs (or profits) of the money waiting aside.

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True, that this difference is not much but I thought as I true mustachian one should also save on such currency exchange fees.

Basically I am trying to find out if the advantage of being longer in the market by investing monthly instead of bi-monthly weighs more in the balance than saving on these 12 CHF fees per year. But as you also say @dbu these opportunity costs are sort of impossible to predict so I will never really know…

You don’t know the opportunity costs, but you do invest in the hope of getting returns, otherwise, why would you do it? We say that historically you had an expected annual return of 7%. Let’s say that you can expect 0.5% return per month. Of course, it can be +10% or -20%, it’s a probability distribution, but we agree that there is a slightly higher chance of gain vs loss.

So if you have 1000 CHF ready to invest right now, you can say that 1 month in the market will be worth about 5 CHF. Already that is higher than the IB fee, so it’s preferable to invest now than wait 1 month.

I have no love for such penny-pinching. We’re all guilty of that, but in the end it’s not worth the time and the nerves. No point to discuss if it’s worth it to spend 2 CHF or not, really.


Thanks @Bojack for your clear example, explained like that it totally makes sense to invest on a monthly basis and ignore the additional currency exchange fees.

I enjoy buying ETFs too much to have to wait 2 months !