A friend sent me a screenshot of his crypto portfolio and asked if it looked reasonable. Fourteen positions. Bitcoin and Ethereum together were maybe a fifth of it. The other twelve were altcoins he had bought at various points, each for a reason that made sense at the time, most of which he could no longer remember. Nobody designs a portfolio like that. It accumulates, one conviction buy at a time, and then one day you look at it and realize you never actually decided what the split between the majors and everything else should be.
The honest answer to how you should divide a crypto portfolio between Bitcoin, Ethereum, and altcoins depends on two things you can pin down without much soul searching: how long you plan to hold, and how much drawdown you can watch without doing something stupid. There is also a neutral starting point that removes the guesswork from the first pass, and it comes straight from the market itself.
Anchor to market cap before you do anything clever
If you owned the entire crypto market in proportion to its size, you would hold roughly half of your portfolio in Bitcoin, a meaningful but much smaller slice in Ethereum, and the remainder spread across everything else. The exact numbers move around over a cycle, and Bitcoin dominance has spent long stretches both above and below the halfway mark, but the shape is stable: one dominant asset, one clear second, and a long tail of thousands of tokens fighting over what is left.
That market-weight portfolio is the closest thing crypto has to a no-opinion position. It is the same logic as buying an index fund instead of picking stocks. Hold the market and the only bet you are making is on the asset class itself. Every deviation from market weights is an active bet, and active bets should be things you can state out loud. Overweight Ethereum because you believe staking yield and fee burn make it structurally undervalued relative to Bitcoin? Fine, that is a position you can defend. Holding 60 percent altcoins because they were exciting when you bought them is also a position, just one nobody would take on purpose.
So the anchor I give people is something like 60 percent Bitcoin, 20 percent Ethereum, 20 percent everything else. It is deliberately boring, it roughly tracks how the market prices the space, and it forces the useful question: where, specifically, do I disagree with the market, and by how much? Everything that follows is about how to move off that anchor deliberately instead of accidentally.
The altcoin sleeve should shrink as your horizon stretches
Here is the part most allocation guides get backwards. People assume a longer horizon justifies more risk, so a five-year holder should load up on altcoins and let time smooth out the volatility. That logic works reasonably well for equities. It fails for altcoins, because altcoins mostly do not mean-revert. They go up violently, and then a large fraction of them never come back.
Look at the coins that ranked near the top of the market a couple of cycles ago. Most are nowhere near those ranks now, and plenty never reclaimed their old highs even when Bitcoin went on to make new ones. Survivorship in the altcoin market is brutal in a way equity investors do not have good intuitions for. A large listed company that falls on hard times usually declines slowly and gets replaced in the index while shareholders exit in an orderly way. An altcoin that loses its narrative can lose 95 percent of its value and just sit there, with no earnings, no buyback, and no mechanical reason to recover beyond hope.
Which means an altcoin position is a trade even when you tell yourself it is an investment. It has an entry, it needs an exit, and the profit only exists once it has been rotated into something with better survival odds. Bitcoin and Ethereum are the only two assets in the space I am comfortable calling holdings, and even that requires some faith. So the relationship runs opposite to the equity intuition: the longer you intend to hold without actively managing, the smaller your altcoin sleeve should be, because the sleeve only earns its keep if someone is there to harvest it. A trader watching positions daily can carry a big alt allocation and take profits on the way up. Someone planning to check the portfolio twice a year should barely carry one at all, since by the second check the gains may have already round-tripped.
Three splits and who they are for
With that in mind, here is roughly how I would map splits to profiles. Treat the numbers as starting points you adjust rather than prescriptions.
- Long horizon, low maintenance. You plan to hold for five years or more and look at the portfolio a few times a year. Roughly 70 percent Bitcoin, 25 percent Ethereum, 5 percent altcoins, and honestly the 5 percent is optional. At this horizon the altcoin sleeve is mostly a hobby allocation.
- Balanced, checked monthly. A horizon of two to four years, and you are willing to rebalance when things drift. Roughly 55 percent Bitcoin, 25 percent Ethereum, 20 percent altcoins, with no single altcoin above a third of the sleeve.
- Active, watched weekly. You are engaged with the market, you take profits, you cut losers. Roughly 40 percent Bitcoin, 30 percent Ethereum, 30 percent altcoins. The heavier alt sleeve is only defensible because you are actually managing it.
Two rules apply across all three. First, cap any single altcoin at a level where it going to zero would be annoying rather than catastrophic, which for most people lands somewhere around 5 percent of the total portfolio. Second, if you cannot explain in one sentence why a token should still exist in five years, it belongs in the active bucket with a planned exit, and it should never migrate into the sleeve you ignore.
Rebalancing is where altcoin gains become real
The mechanics matter more than the initial split, because the initial split will not survive contact with a bull market. Altcoins can triple while Bitcoin doubles, and suddenly your 20 percent sleeve is 35 percent of the portfolio. You are now far riskier than you decided to be, at exactly the point in the cycle when risk is most expensive.
My rule is simple threshold rebalancing with a one-way valve. When the altcoin sleeve drifts more than about five percentage points above target, trim it back and move the proceeds into Bitcoin and Ethereum at your target ratio. That direction is mechanical, no judgment involved, because trimming winners into the majors is how paper gains turn into something that tends to still be there next cycle. The other direction is manual. When the alt sleeve crashes below target, I do not automatically buy it back up to weight, because unlike an equity index, a basket of bleeding altcoins has no built-in reason to recover. Refilling the sleeve should be a fresh decision about which specific tokens deserve the money, made deliberately, token by token, and sometimes the right answer is to leave the sleeve underweight for a year.
Put a calendar reminder on it, quarterly is enough for the slower profiles. And know the failure mode in advance, because it catches almost everyone once. The sleeve runs hot, you skip the trim because selling feels like leaving money on the table, and then the cycle turns and the entire excess evaporates within a few months. Nearly every crypto investor I know has one round trip like that in their history. The rebalancing rule exists so you only do it once.
Taxes are the honest objection here. Trimming triggers taxable events in most jurisdictions, and that is a real cost. Historically it has tended to be smaller than the cost of riding a heavily overweight altcoin sleeve back down, but run your own numbers before deciding.
I track the drift with Blockcircle's portfolio tools because that is where the rest of my market data already lives, but a spreadsheet and a recurring reminder do the same job. Pick the profile that matches how often you will honestly look at this thing, write the three numbers down, and let the written version overrule you when the market starts arguing with it. The split you decide on a calm day is almost always better than the one you improvise in the middle of a cycle.