Memory Stock Map Explained: DRAM, NAND and HBM Makers in One View

The Memory map on Pacific Tape draws 12 stocks listed in four markets: the companies that make memory chips, and the equipment makers whose tools stack and test high-bandwidth memory (HBM). The size of a box is the company’s market value in US dollars. The color is how much its share price moved. Green means up, red means down and gray means unchanged.

Three boxes dominate, so read the sizes first. On October 23, 2026, the map added up to about US$3.38 trillion, and Micron, Samsung Electronics and SK hynix covered 78.4% of it. The examples below all come from that day.

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Which stocks are on the Memory map?

All 12 are also on the Chips map, and each carries one of two roles:

Role	Companies (market)
Memory	Samsung Electronics, SK hynix (Korea); Micron, SanDisk (US); Kioxia (Japan); Nanya Technology, Winbond, Phison (Taiwan)
Equipment	Hanmi Semiconductor (Korea), Advantest, Disco, Tokyo Electron (Japan)

The memory group holds seven memory-chip makers and Phison, which designs controllers for flash memory. The equipment group holds four companies whose tools are used to build HBM: Hanmi’s bonders, Advantest’s testers, Disco’s grinding and dicing machines and Tokyo Electron’s process equipment. Smaller memory names below US$10 billion, such as Macronix, Rambus and Silicon Motion, are left out, and so are the hard-drive makers Seagate and Western Digital.

One thing to keep in mind: a box is the whole company. Samsung Electronics’ box includes its phones, displays and appliances, not only its memory business. Who Makes What in Memory covers which company makes DRAM, NAND and HBM.

What do the box sizes mean?

A box’s area is the company’s market value, its shares times its latest closing price, converted to US dollars at Bank of Korea (ECOS) exchange rates. For October 23 those were 1,324.6 won, 156.55 yen and 32.613 New Taiwan dollars per dollar. Market value is not adjusted for free float.

On October 23:

Company	Share of the map
Micron	29.38%
Samsung Electronics	28.14%
SK hynix	20.84%
SanDisk	5.29%
Advantest	4.47%

Those five covered 88.1% of the map; the smallest boxes, Hanmi Semiconductor and Phison, were 0.41% and 0.38%. By market, Korea was 49.4%, the US 34.7%, Japan 13.6% and Taiwan 2.3%.

Two menus change the layout:

1. Box size: Market value (the default), Square root, which shrinks the gap between the biggest and smallest boxes, or Within group.
2. Group: By role (Memory, Equipment) or By country (Korea, Taiwan, Japan, United States).

What do the colors mean?

The color is the move over the period you pick: the latest session, Previous day, or 5D, 20D, 60D and 120D, counted in each market’s own trading days. For one day the shades step at 0.5%, 1%, 2% and 3% each side; the steps widen for longer periods. A move under 0.005% is gray.

On October 23 the memory group rose 1.78% weighted by market value and the equipment group fell 0.40%. SK hynix had the biggest gain, up 4.42%; Nanya Technology had the biggest fall, down 5.15%, in its October 22 session.

Why can the headline move and the typical stock disagree?

Below the map the page shows the size-weighted move, a Markets line with each market’s session, the median stock and up · down · flat. On October 23 the size-weighted move was +1.55%, while the median stock was −0.10% and only 5 of the 12 stocks rose. The three largest boxes all rose, so they pulled the weighted figure up even though most of the smaller names fell.

Which day is the map showing?

The four markets close at different times, so the status line shows a badge for each, KRX, TSE, TWSE and Nasdaq, with its latest close. Each box uses its own market’s latest regular-session close. In the October 23 data, the Korean, Japanese and US stocks showed October 23 and the Taiwanese stocks October 22, which the Markets line spelled out as “KRX Oct 23 · TWSE Oct 22 · TSE Oct 23 · Nasdaq Oct 23.” Japanese and Taiwanese prices during the trading day are 20 minutes delayed. One Chip Day, Four Closes explains how the four sessions fall in one day.

What can the Memory map tell you, and what can’t it?

It shows how the memory makers and their HBM suppliers compare in size and how they moved over one period, across four markets at once. It does not separate memory from a company’s other businesses, and one session’s colors say nothing about the next. For the wider chip sector, see the Chips map explainer.