# 填权 (Gap Fill) Timing Reference

## What is 填权?

After ex-dividend, the stock price drops by approximately the dividend amount. "填权" means the stock price recovers back to (or above) the pre-ex-dividend level over time.

**填权 ≠ immediate.** The market doesn't give away free money — the ex-div price drop is a mechanical adjustment. Whether and how fast the gap fills depends on ongoing supply/demand for the stock.

## Historical Fill Speeds for A-share Dividend Stocks

### 华特达因 (000915) — High-dividend healthcare stock

| Year | Ex-div | Dividend | Pre-close | Ex-close | Fill Time | Notes |
|------|--------|----------|-----------|----------|-----------|-------|
| 2025 | Jun 11 | 2.00元 | 32.39 | 29.49 | **~10 days** (31.15, +5.6%) | Fast fill; stock was in uptrend |
| 2024 | May 16 | 2.00元 | 35.30 | 33.48 | **Did not fill in 60 days** (30→27) | Bear market dragged it down |

**Key insight:** 2025 filled fast because the stock was in a healthy trend. 2024 didn't fill because the overall market was falling. Stock quality matters but macro conditions dominate.

### 同仁堂 (600085) — Blue-chip TCM

(Add data here when available from analysis.)

## Factors That Determine Fill Speed

### 1. Stock Price Position (Most Important)

```
Stock at 52-week low:   High fill probability (already "cheap")
Stock at 52-week high:  Low fill probability (due for pullback)

Example: 华特达因 2025 → ex-div at 32 → near YTD high → fast fill anyway (good stock)
         华特达因 2024 → ex-div at 35 → at YTD high → no fill (bad timing + bad market)
```

### 2. Market Direction

- **Bull market / 结构性牛市**: Most quality stocks fill within 1-3 weeks
- **Bear market / 熊市**: Can take months or never — the dividend is "eaten" by the falling price
- **Sideways market**: Depends on stock-specific catalysts

### 3. Dividend Size Relative to Price

| Dividend/Price ratio | Impact |
|---------------------|--------|
| < 2% | Small gap, easy to fill (days) |
| 2-5% | Moderate, 1-3 weeks typical |
| > 5% | Large gap, may take months; better to wait for natural dip before buying |

### 4. Company Fundamentals

- **Growing dividends** (e.g., 华特达因 2021: 0.35 → 2025: 2.50/share) → faster fill (market rewards increasing payouts)
- **Stable/declining dividends** → slower fill
- **High payout ratio** (>80%) → risk of cut → may never fill
- **Cash-rich** (>30% market cap in cash) → faster fill (dividend is safe)

## Practical Rules for Dividend Capture

```
If you MUST try dividend capture (buy pre-ex-div, sell post):

1. Only attempt on stocks near their 52-week LOW
   → The ex-div gap is less damaging when already near support

2. Only attempt when market is in uptrend
   → Check: is the SH/SZ index above its 50-day MA?

3. Plan to hold MINIMUM 2-4 weeks post-ex-div
   → Selling the next day guarantees a loss (tax + gap)

4. Calculate your break-even price:
   BreakEven = ExDivPrice + (Tax_Rate × Dividend)
   
   Example: 28元 stock, 2元 dividend, 20% tax:
   BreakEven = 26.00 + 0.40 = 26.40
   → Stock must rally 1.5% from ex-div just to break even

5. Consider buying AFTER ex-div instead:
   - No dividend → no tax → no gap risk
   - Lower entry price → higher yield on cost
   - Same future dividends
   → Often the better move for pure yield investors
```

## Data Source

To calculate 填权 timing for any stock:

```python
import akshare as ak

# Use unadjusted prices (adjust='') to see the real ex-div gap
df = ak.stock_zh_a_hist(symbol='000915', period='daily', 
                         start_date='20250601', end_date='20251001', adjust='')

# Find ex-div day by looking for the big drop on the expected date
# Then scan forward to see how many days to recover
```
