10 Virtu Financial Software Engineer (New Grad) Interview Questions (2026)

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STAR. Pick a real bug — race condition, memory corruption, performance regression. Walk through diagnosis (tools used, hypothesis testing), root cause, fix, what you learned. Virtu values systematic debugging. Avoid heroic guesses.

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Specific reasons: publicly-traded firm with transparent financials, multi-asset coverage (equities, fixed income, FX, crypto, options), strong client-execution business in addition to prop trading, large engineering team with diverse projects. Reference Virtu's growth history (KCG, ITG acquisitions). Avoid 'high pay' as the lead.

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Expand around center. For each index, expand for odd-length (single center) and even-length (two-center) palindromes. Track longest. O(n^2) time, O(1) space. Walk through example. Mention Manacher's O(n) for theoretical interest but rarely required in interviews.

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Sort by start. For each interval, check pairs with subsequent intervals whose start is before the current's end. Sweep line approach: O(n log n + k) where k is output. Walk through example. Discuss extension to point-in-interval queries (interval tree).

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For each word, sort characters as the anagram key (or use a 26-element frequency array). Group words by their key in a hash map. Return groups. O(n·k log k) time where k is max word length. Walk through example. Alternative: count vector as key (k = 26 for English).

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Single mutex around hash map + doubly-linked list. Get: lock, lookup, move to head, unlock. Put: lock, update or insert, evict if needed, unlock. O(1) per operation. Mention sharded approach (multiple buckets each with own lock) for higher concurrency. Walk through code.

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TCP: connection-oriented, reliable, ordered, flow control, congestion control. UDP: connectionless, unreliable, fast, no overhead. Use TCP for: correctness-critical (HTTP, SSH, file transfer). Use UDP for: latency-critical (DNS, video, market data). In trading: UDP multicast for market data (one-to-many efficiency); TCP for order entry (where reliable delivery matters). Discuss why HFT prefers UDP and how applications add reliability on top.

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Cache line: smallest unit transferred between cache levels, typically 64 bytes. Implications: (1) Spatial locality — accessing adjacent memory is fast (already loaded). (2) False sharing — two threads writing different variables in same line causes coherence traffic. (3) Layout matters: array-of-struct vs struct-of-array affects cache utilization. Discuss in trading context where every microsecond matters.

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Runtime detection: tools like Helgrind (Valgrind), ThreadSanitizer detect lock ordering violations. Static analysis: code review for consistent lock ordering. Watch for: nested locks, blocking calls while holding locks. Prevention: always acquire locks in same order globally, use lock-free data structures where possible, use timed locks (try_lock with timeout). Discuss real-world example where you applied these.

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Layered: (1) Receive: per-feed kernel-bypass NIC, dedicated thread per feed. (2) Parse: vendor-specific protocol (FIX, ITCH, OPRA). Zero-copy in hot path. (3) Normalize: convert to internal representation. (4) Distribute: lock-free queues to consumers, drop policy for slow consumers. Discuss latency budget per layer; total goal ~10us end-to-end. Discuss multi-feed arbitration (timestamp alignment).