Here are a few options for describing the “index fund” post tag in Traditional Chinese, along with explanations to guide your choice:

**Option 1 (Most Common and Straightforward):**

* **標籤描述:** 追蹤指數的共同基金 (Zhuīzōng zhǐshù de gòngtóng jījīn)
* **Explanation:** This translates to “Common fund that tracks an index.” It’s clear, concise, and suitable for a broad audience. “追蹤指數” (zhuīzōng zhǐshù) means “to track an index” which is a key characteristic of index funds. “共同基金” (gòngtóng jījīn) means “mutual fund” or “common fund,” which is technically correct and easily understood.

**Option 2 (Emphasizing Passive Management):**

* **標籤描述:** 被動型指數基金 (Bèidòng xíng zhǐshù jījīn)
* **Explanation:** This translates to “Passive index fund”. This emphasizes the ‘passive’ nature of these funds. This phrase is common in financial discussions and will be understood by anyone interested in finance. If your blog covers actively managed funds, this is especially good to contrast.

**Option 3 (More Detailed for Beginners – but also longest):**

* **標籤描述:** 追蹤特定市場指數、旨在複製其表現的共同基金，如股票市場指數。（Zhuīzōng tèdìng shìchǎng zhǐshù, zhǐ zài fùzhì qí biǎoxiàn de gòngtóng jījīn, rú gǔpiào shìchǎng zhǐshù.)
* **Explanation:** This translates to: “A common fund that tracks a specific market index, aimed at replicating its performance, such as a stock market index.” This offers a bit more detail making it suitable for beginners unfamiliar with index funds. “追蹤特定市場指數” (zhuīzōng tèdìng shìchǎng zhǐshù) means to, “track a specific market index”. “旨在複製其表現” (zhǐ zài fùzhì qí biǎoxiàn) means “aimed at replicating its performance”. “股票市場指數” (gǔpiào shìchǎng zhǐshù) means, “stock market index” (e.g., S&P 500).

**Option 4 (Shorter and More Catchy):**

* **標籤描述:** 指數投資 (Zhǐshù tóuzī)
* **Explanation:** This translates to “Index Investing”. This is a more general term and can be helpful if your blog also covers broader topics like the philosophy of index investing, how to invest in index funds, and other similar related activities.

**How to Choose:**

* **Audience:** Consider whom you are writing for. If they are finance-savvy, options 1 or 2 are great If they are new to investing, options 3 might be a little better.
* **Blog Content:** Choose the description that best aligns with your post’s content and focus. If you are just covering individual index, option 1 will be fine.

**How to Add the Description in WordPress:**

1. **Go to “Tags” (or “Categories” if you are using categories instead).**
2. **Edit the “index fund” tag.**
3. **Look for a field labeled “Description” or “Tag Description.”** (This field may be hidden. Click on “Screen Options” at the top right of your WordPress admin screen, and make sure “Description” is checked.)
4. **Enter your chosen Traditional Chinese description.**
5. **Update the tag.**

I recommend Option 1 or 2 for most purposes because they are clear and concise. However, choose the one that best suits your needs. Good luck!