# Trading API FAQs

> Common questions about MyStocks quotes, orders, fractional investing, settlement, and retries.

## Why do I need a quote before a market trade?

The quote binds the expected symbol, side, quantity or cash value, and expiry window. This prevents stale pricing and accidental payload changes between pricing and order submission.

## Can I trade fractions?

Use `cashValue` where fractional investing is enabled. Whole-share markets require integer `quantity`; do not send both fields.

## Is a successful order response a fill?

No. Follow the order lifecycle and wait for execution or settlement state. Use the order endpoint, webhooks, or SSE to observe transitions.

## How do I retry a failed request?

Retry only with the same `Idempotency-Key`. The SDKs retry safe reads and idempotent writes for transient statuses; non-idempotent writes are not automatically retried.