```python
from fastapi import FastAPI, Query
from fastapi.responses import JSONResponse
import helpers  # noqa: F401

app = FastAPI()


@app.get("/portfolio")
async def get_portfolio(symbols: str = Query(...)):
    # Split symbols by comma, strip whitespace
    symbol_list = [s.strip() for s in symbols.split(",") if s.strip()]
    # Launch coroutines for all symbols simultaneously
    prices = await asyncio.gather(*(helpers.afetch_price(sym) for sym in symbol_list))
    return JSONResponse(content={"prices": dict(zip(symbol_list, prices))})
```