This is also happening in the US to some degree, fewer companies are going public and prefer to stay private longer, many times by letting investors/shareholders get some liquidity via private equity injection of capital. The way I try to protect myself against this is:
1) Heavily diversify in international (50% of my equity portfolio is in ex-us index funds), where the declining trend is not as sharp.
2) Tilt my equity allocation towards small cap value (20% tilt). Small cap value has been shown by academics to be a good proxy for private companies that a normal investor in the public market cannot typically own.
Hmm, I don't think its the same thing though. The US has multiple stock exchanges and many different cities hyper-specializing in different things (e.g. SF- Tech, Chicago-Commodities, NYC-Finance, Houston-Energy). The country itself is a powerful economic engine with all that land and close to 300 million people.
In comparison: the only reason Singapore did so well because economic activity in APAC needed to be directed from an English speaking country in the region which was stable and had a well established corporate laws/governance.
Now that other countries are catching up, Singapore is rapidly losing that advantage.
It could be a sign of increasing inequality. The super-rich can easily invest in private companies as they desire, and the company doesn't have to conform to public stock requirements and regulations. In other words, they don't have have to care about the 99% because the 99%'s funds are becoming too small to offset the downsides of going public.
I have ~$1.5M (USD) invested according to what I said (80/20 equity/fixed, and the equity portion 50/50 us/ex-us), representing 99% of what I own. I contribute about 150k/yr to the same allocation, via normal savings. I do that in good times and bad times, no matter what.
If I were in your shoes, I would evaluate what is the 4% for: if it's for a mortgage, I'd keep it (you get a tax deduction after all). If not, it's essentially a tie: I'm fairly comfortable assuming that over the long run my above portfolio will beat 4% IRR, but at the same time getting a guaranteed 4% return by paying that non-deductible debt is not bad either.
1) Heavily diversify in international (50% of my equity portfolio is in ex-us index funds), where the declining trend is not as sharp.
2) Tilt my equity allocation towards small cap value (20% tilt). Small cap value has been shown by academics to be a good proxy for private companies that a normal investor in the public market cannot typically own.
I hope it'll be enough!