```python
from fastapi import FastAPI
import helpers
import asyncio

app = FastAPI()


@app.get("/portfolio")
async def portfolio(symbols: str):
    # Split the comma-separated list, strip whitespace, and ignore empty parts
    sym_list = [s.strip() for s in symbols.split(",") if s.strip()]
    # Fetch all prices concurrently using the async helper
    prices = await asyncio.gather(*[helpers.afetch_price(sym) for sym in sym_list])
    # Build the result dictionary
    result = dict(zip(sym_list, prices))
    return {"prices": result}
```