Personal Finance Notes: Asset Allocation and Investment Policy

Notes on personal investing. Written to document my own thinking, not to recommend anything to anyone.

Core Principles

• Index investing as the core, with individual stocks and ETFs as satellite
• Keep 6 months of living expenses in cash before investing anything
• Diversify between JPY and USD to manage currency risk

Accounts and Services

Core Portfolio (Index)

Global equities (eMAXIS Slim All Country): 40%
US equities (S&P500):                      30%
Bonds (domestic + international):          10%
Cash / dry powder:                         20%

Fixed monthly contributions regardless of market conditions. No market timing.

Satellite (Individual Stocks and ETFs)

Criteria:

• Only companies I understand the business of
• Prefer large-cap, high-liquidity names
• Thematic ETFs (e.g. AI) only after the hype cools down

Sectors I’m watching:

• AI and data centers — infrastructure spend looks durable (NVIDIA, AMD, SMCI adjacent)
• Japan defense and semiconductors — policy tailwind
• Japanese high-dividend stocks — JPY-denominated dividends reduce currency exposure

Individual stocks are capped at 20% of total portfolio. Concentration raises both upside and downside.

Tax Structure (Japan)

NISA (new system from 2024)

The old NISA (general and accumulation types) stopped accepting new contributions at end of 2023. Existing holdings continue as-is.

iDeCo: Not enrolled yet. For company employees, the contribution limit depends on whether the employer has a corporate DC plan — still working this out.

Currency Risk Management

In a weak-yen environment, USD-denominated assets look better in dollar terms, but buying them costs more in yen.

My approach:

• Keep monthly contributions fixed (averages out over time)
• Wait for yen strength before lump-sum purchases
• Exchange currency through Sony Bank (lower spread) before moving to brokerage

Tools I Use

• Money Forward ME — aggregates all accounts and securities in one view
• Google Sheets — my own tracking and calculations
• SBI Securities portfolio page — sector breakdown for ETFs

Money Forward is useful but seeing real-time balances makes it tempting to check too often. For long-term investing, once a month is enough.

Open Questions

1. iDeCo — run the numbers on tax savings vs. liquidity tradeoff
2. REITs — direct real estate is out of scope, but J-REITs are worth looking at
3. USD-denominated insurance — currently not convinced it makes sense
4. Dividend reinvestment — want to automate this more efficiently

This is a personal memo, not financial advice.