How many houses are not sold publicly/funda?

When we were looking to buy a house we did not use a purchase broker (aankoopmakelaar), but instead looked for houses ourselves online (mostly via funda.nl). One thing we often heard was that we’d miss houses were sold silently, from broker to broker. To verify this rumour, I bought kadaster data of recently sold houses (kadaster.nl) in our neighbourhood and checked whether I could find these online.

Findings:

1. 18 out of 20 houses had advertisements online
   1. 10 on funda
   2. 8 only on local brokers
   3. 2 houses were not advertised publicly, where one was sold at a very low price (perhaps sold to relatives?)

Method:

1. Buy a few zip code reports from the kadaster (kadaster.nl)
2. For each house sold recently, search on google/funda

Conclusion: 90% of houses for sale are available online, of which at least 50% on Funda (some might have expired), and 40% on local websites. The hidden market could be limited to 10%.

Update 20191020: replies disabled because of spambots

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