Author:Leto Bao, the protagonist of becoming financially free with thirty million from stock trading in Byte

All the following information was shared in the Byte US stock group last year, including trading targets, position gains and losses, all verifiable

Last August, I initially just wanted to buy two hard drives.

At that time, I was setting up a small quantitative platform for myself, wanting to pull some tick-level market data to save locally. I needed space for tens of terabytes of data, so I ordered two large-capacity hard drives from Seagate on Pinduoduo. Looking back now, this hard drive marked the starting point of my storage investments over the past two years.

Hard drive prices began to change daily

After receiving the hard drives, I saved the link in case I needed more. After a few days, I checked again, and the price had increased; a few days later, it rose again. The same model, from the same store, had multiple price adjustments within a week, and it only increased.

For an industrial product that is highly standardized and has a large production capacity, the retail price should not continue to rise unidirectionally like this. I regarded it as an abnormal signal worth investigating deeply, rather than just a simple price increase by the seller.

I used price comparison tools like Shenzhou Buy and Keepa to pull out the price curve of this hard drive over the past few months and compared it with several other large-capacity models from Seagate and Western Digital. The conclusion was consistent: this wasn’t a problem limited to a single model; the entire product line of large-capacity mechanical drives was increasing, and it was a sustained, unidirectional rise, not like short-term fluctuations caused by promotions.

At this point, it could be confirmed that there was a bigger reason behind it.

Following this line of inquiry leads to AI snatching hard drives

As I delved deeper, the logic gradually became clearer.

The market pays more attention to AI's demand for graphics cards, but its demand for storage is also enormous. Large model training and inference generate massive amounts of data that need to be stored long-term, and long-term, low-cost data storage mainly relies not on SSDs but on large-capacity mechanical hard drives. These drives used in data centers are called nearline enterprise-level hard drives, and large cloud providers like Microsoft, Amazon, Google, and Meta are purchasing them in large quantities.

Seagate happened to be at the center of this wave of demand. Its promoted HAMR technology significantly increases the single-drive capacity, which aligns perfectly with the needs of data centers. With limited production capacity, manufacturers prioritize supplying more profitable enterprise-level orders, which squeezes the supply on the retail side. The price increase I saw on Pinduoduo essentially reflects the procurement demand from AI data centers, which has been transmitted all the way to consumer prices.

I checked Seagate's financial report at that time: the most recent quarter saw a 39% year-over-year revenue growth, and the gross profit margin hit a record high, with the market also beginning to price the data storage sector as a part of the AI industrial chain.

After confirming the logic, I purchased 500 shares at over 150 dollars and shared my buying rationale, costs, and position in the company's internal US stock group chat.

What made me confident to increase my position was the upcoming 13F

Understanding my own reasoning wasn’t enough; I needed to confirm whether institutional funds were also making the same judgment.

In the US stock market, there is very useful public data: institutions managing over one hundred million dollars must disclose their US stock holdings every quarter, known as 13F. This is equivalent to a legal, public record of institutional holdings, which anyone can look up.

I didn’t increase my position immediately; instead, I wanted to observe the trend over one or two more quarters. A single-quarter change could be coincidental, but a continuous trend over several quarters is more credible. By the time the November issue, which was the 13F for the third quarter, was released, I connected the institutional holdings of Seagate over the past year into a line, and the direction was already very clear:

In the second half of 2024, this stock was essentially overlooked, with the number of institutions holding it remaining at over eight hundred, even slightly declining. However, in the second quarter of 2025, it clearly turned a corner, and in the third quarter, it accelerated further: the number of institutions holding it increased from over eight hundred to over twelve hundred, and the number of new institutions entering each quarter also rose.

It is worth noting that the market value of holdings increased to 45.6 billion within a year, a significant part of which came from the stock price increase itself, not all from new funds. However, metrics like the number of institutions and the number of new positions, which reflect "breadth," provide a clearer picture; their quarter-over-quarter increase indicates that this is not just a bet from one or two funds, but sustained entry from a group of professional funds.

Once I confirmed this, I felt more confident in significantly increasing my position and began to study the storage sector seriously, subsequently starting to continue building my position through LEAPS CALL in $STX and $SNDK.

Looking back now

On the day I bought the hard drives, Seagate closed at over 150 dollars; today it is over 965 dollars, having increased more than six times, and last year at one point surpassed Palantir to become the S&P 500's top stock in annual growth. Just from that initial 500 shares, the paper profit is about four hundred thousand dollars, and I will not detail the subsequent additions.

Ultimately, these two hard drives led to such a trade; looking back, it is still somewhat unexpected.

Summarizing this line of thought

It's actually not complicated:

• Abnormalities in everyday items (price increases, stock shortages, queues) often appear earlier than news and financial reports. Ordinary people can sometimes receive firsthand signals sooner than professional institutions.

• Don’t stop at the impression of “it seems to have become more expensive.” By charting the price as a curve, you can basically judge whether it is a trend or noise.

• Further question: Is there a long-term, structural demand behind this? Then find publicly traded companies that can directly benefit from it and are positioned in key locations in the industry chain.

• Finally, verify institutional attitudes using 13F, and observe trends over several consecutive quarters rather than a single quarter.

This method does not guarantee correctness every time, but at least it allows purchases to be based on logic rather than intuition.

Finally, clarifying the risks

This was a successful trade. I have also experienced situations where I fixated on a price increase signal, which turned out to be just a short-term fluctuation; those were not shared in the group but still existed, and survivor bias is quite evident.

The above is a personal review and does not constitute investment advice; profits and losses are at one's own risk.

However, I endorse this line of thought: pay attention to the abnormalities you encounter daily, inquire a layer deeper into the reasons, identify the underlying publicly traded companies, and then check 13F to see if professional funds agree. Next time something you frequently buy inexplicably increases in price, you might want to ponder: who is benefiting from that money, and is that company already publicly traded?

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