An epic bond-buying spree by Japan's central bank means it's now sitting on assets worth more than the country's entire economy.

Data released by the Bank of Japan on Tuesday show that its total holdings stand at 553.6 trillion yen ($4.9 trillion) following years of money printing aimed at jump starting the country's stagnant economy. That's bigger than Japan's annual gross domestic product at the end of the second quarter — and more than five times the size of Apple's (APPL) market value.

The years of heavy stimulus have warped parts of Japan's financial markets and left the central bank with dwindling options to juice growth if a new crisis hits. But the splurge is unlikely to end anytime soon.

The Bank of Japan has accumulated most of the enormous stockpile of assets since its governor, Haruhiko Kuroda, embarked on an unprecedented plan in 2013 to buy vast amounts of government bonds. Its goal was to push down interest rates, encouraging consumers and businesses to spend more money.

The move was similar to the extraordinary monetary easing programs launched in the United States and Europe in the aftermath of the global financial crisis. But Japan's is far greater in scale in relation to the size of its economy.

The US Federal Reserve's total assets are about one fifth of the size of US GDP, and the European Central Bank's are around 40% of the eurozone economy.

The Fed announced a halt to its bond-buying spree in 2014 and is now raising interest rates, and the ECB will stop its program next month. But the Bank of Japan's binge has no end in sight. (CNN)