**Appendix A**

*Appendix A.1 Model 1. OLS Model Description*

The purpose is to find a model that can approximate a target function, which can be written as:

$$r\_{i+1} = \alpha + \beta\_1 X\_{i,1} + \beta\_2 X\_{i,2} + \dots + \beta\_N X\_{i,N} + \varepsilon\_i \tag{A1}$$

where *ri* is the BTC price at month *i* + 1. *Xi*,1 *to Xi*,*<sup>N</sup>* are attributes at day/month *i* which is described as follows:

*Xi*,1: BTCs in Circulation in month *i* is the total number of mined BTC currently circulating on the network.

*Xi*,2: Market capitalization in the month *i* is calculated by multiplying the total number of BTCs in circulation by the BTC price.

*Xi*,3*:* Block size in month *i* imposes a limit on the number of transactions that can be verified on each block. As a result of such a mechanism, larger blocks require more processing power and longer extraction time.

*Xi*,4: Average block size in month *i*.

*Xi*,5: Orphaned blocks in the month *i* are blocks that are not accepted into the blockchain network, which is created due to the delay in receiving a block, at which point another miner responds to the same block. Orphan blocks are valid, but do not register any transaction and have been rejected by the chain.

*Xi*,6: Number of transactions per block in month *i* are the transactions that happen in a block, and as soon as a block is solved, it is not possible to extend the block by adding more transactions.

*Xi*,7: Median confirmation time in month *i* is the median time for dealing with miners' fees enclosed in a mined block and superimposed to the public ledger.

*Xi*,8: Hash rate in day/month *i* is the speed at which computational operations are completed to mine a BTC block.

*Xi*,9: Mining difficulty in month *i* is a measure of how difficult it is to mine a BTC block, or in more technical terms, to find a hash below a given target.

*Xi*,10: Transaction fees in month *i* are paid when cryptocurrencies are transferred to another wallet. Processing transactions on the blockchain takes effort, and these fees are used to compensate the miners and validators who help keep things running smoothly.

*Xi*,11: Cost per transaction in month *i* is calculated as miners' revenue divided by the number of transactions.

*Xi*,12: Unique addresses in month *i* are installment addresses that have a non-zero adjust. This metric is one way of understanding day-by-day utilization of the BTC arrangement.

*Xi*,13: Total BTC transactions in month *i*.

*Xi*,14: Transaction volume excluding popular addresses in month *i* is the total number of transactions excluding those involving the network's 100 most popular addresses.

*Xi*,15: Total output value in month *i* is the total value of all transaction outputs, including coins, returned to the sender as change.

*Xi*,16: Estimated transactions value in month *i* is the total estimated value in BTC transactions on the blockchain, which does not include coins returned as change.

*Xi*,17: Nasdaq Composite is a stock market index of the common stocks and similar securities listed on the Nasdaq stock market.

*Xi*,18: Dow Jones Industrial Average (DJIA) index in month *i* is a stock market index that measures the stock performance of 30 large companies listed on stock exchanges in the United States.

*Xi*,19: S&P500 stock market index in month *i* is a stock market index that measures the stock performance of 500 large companies listed on stock exchanges in the United States.

*Xi*,20: Gold-fixing price in month *i* is the setting of the gold price that takes place via a dedicated conference line. The price continues to be set twice daily at 10:30 and 15:00 London GMT in US dollars.

*Xi*,21: West Texas Intermediate crude oil (WTI) prices or Texas light sweet in month *i* is a benchmark in oil pricing, refined mainly in the Midwest and Gulf Coast regions in the United States.

*Xi*,22: US federal funds rate in month *i* is the interest rate at which depositors trade federal funds with each other at night. When a depository institution has a surplus in its reserve accounts, it can lend to other banks that need those funds. In other words, a bank with extra cash can lend it to another bank with a liquidity problem, and thus the cash balance of a bank with a problem with cash increases rapidly.

*Xi*,23: Breakeven inflation rate in month *i* is a measure of expected inflation, the difference between a nominal bond's yield and an inflation-linked bond with the same maturity.


**Table A1.** Descriptive statistics.

**Table A2.** VIF for choosing attributes.


**Table A2.** *Cont.*


'\*' VIF greater than 10.

**Table A3.** OLS regression results.


'\*\*\*' Significant at the 0.001 level, '\*\*' Significant at the 0.01 level, '\*' Significant at the 0.05 level, '.' Significant at the 0.1 level.
