Negative yielding Government debt (the case where investors pay the sovereign lenders for the privilege of lending them funds) has hit all-time record (based on Bloomberg database) last week, at 13 trillion.
Source of charts: https://www.bloomberg.com/amp/news/articles/2019-06-21/the-world-now-has-13-trillion-of-debt-with-below-zero-yields.
Quarter of all investment grade corporate debt is now also yielding negative payouts (note: bond returns include capital gains, so as yields fall, capital gains rise for those investors who do not hold bonds out to maturity).
In effect, negative yields are a form of a financialized tax: investors are paying a premium for risk management that the bonds provide, including the risk of future decreases in interest rates and the risk of declining value of cash due to expected future money supply increases. In other words, a eleven years after the Global Financial Crisis, the macro-experiment of monetary policies 'innovations' under the QE has been a failure: negative yields resurgence simply prices in the fact that inflationary expectations, growth expectations and financial stability expectations have all tanked, despite a gargantuan injection of funds into the financial markets and financial economies since 2008.
In 2007, total assets held by Bank of Japan, ECB and the U.S. Fed amounted to roughly $3.2 trillion. These peaked at just around $14.5 trillion in early 2018 and are currently running at $14.3 trillion as of May 2019. Counting in China's PBOC, 2008 stock of assets held by the Big 4 Central Banks amounted to $6.1 trillion. As of May 2019, this number was $19.5 trillion. Global GDP is forecast to reach $87.265 trillion by the end of this year in the latest IMF WEO update, which means that the Big-4 Central Banks currently hold assets amounting to 22.35% of the global nominal GDP.
Negative yields, and ultra-low yields on Government debt in general imply lack of incentives for Governments to efficiently allocate public spending and investment funds. This, in turn, implies lack of incentives to properly plan the use of scarce resources, such as factors of production. Given that one year investment commitments by the public sector usually involve creation of permanent or long-term subsequent and related commitments, unwinding today's excesses will be extremely painful economically, and virtually impossible politically. So while negative yields on Government debt make such projects financing feasible in the current economic environment, any exogenous or endogenous shocks to the economy in the future will be associated with these today's commitments becoming economic, social and political destabilization factors in the future.