Interview guides · Janney Montgomery Scott

Janney Montgomery Scott Software Engineer Interview Guide

Janney Montgomery Scott Software Engineer interview guide: reported rounds, questions and how candidates describe the process.

The 60-second brief

As a Software Engineer at Janney Montgomery Scott, you play a critical role in building, maintaining, and modernizing the digital infrastructure of a leading full-service wealth management and investment banking firm. The applications you develop directly support financial advisors, investment professionals, and clients, ensuring secure, high-performance execution of financial transactions and wealth management strategies. At Janney Montgomery Scott, technology is not just a support function; it is a strategic driver of business growth and client satisfaction. You will work extensively within the Microsoft (MS) technology ecosystem, integrating enterprise-grade applications with complex financial databases and modern cloud architectures. The systems you build must handle high-throughput financial data while maintaining strict security compliance and operational stability.

This guide is scoped to a Software Engineer candidate at Janney Montgomery Scott.

Focus areas

Phone Screen Interviews
HR Interviewing
Hiring Manager Technical Interview

The Janney Montgomery Scott interview process

Janney Montgomery Scott candidates report 3 rounds over 3-5 weeks. The stages below are what candidates describe, not a published process.

Recruiter Screen

Initial conversation with a recruiter or HR representative focusing on career history and soft skills.

What to demonstrate

Initial conversation with a recruiter or HR representative focusing on career history and soft skills
Depth in Phone Screen Interviews

How to prepare

Be able to walk your CV end to end in two minutes, and say why this company specifically.
Have your salary expectations, notice period and location constraints ready, and ask for the rest of the loop in writing.

Technical Screening

Technical conversation with a hiring manager assessing experience with the Microsoft ecosystem and enterprise applications.

What to demonstrate

Technical conversation with a hiring manager assessing experience with the Microsoft ecosystem and enterprise applications
Depth in Phone Screen Interviews

How to prepare

Answer aloud and timed: How do you approach learning a new business domain or complex application architecture when joining a new team?
Answer aloud and timed: Describe a time when you had to optimize a slow-performing legacy application. What was your process?

Onsite Interview

Comprehensive interview with multiple team members to evaluate system design capabilities and behavioral alignment.

What to demonstrate

Comprehensive interview with multiple team members to evaluate system design capabilities and behavioral alignment
Depth in Phone Screen Interviews

How to prepare

Answer aloud and timed: How do you ensure data integrity and security when integrating multiple third-party applications?
Answer aloud and timed: What are the key differences between various architectural patterns, such as microservices and monolithic architectures, and when would you choose one over the other?

Where candidates lose points

Prepare your elevator pitch

Since the initial HR screen and subsequent interviews heavily feature a walk-through of your career history, have a polished, 2-minute summary of your professional journey ready.

Master the Microsoft ecosystem

Be ready to speak in detail about C#,.NET, and SQL Server. Brush up on core concepts like dependency injection, entity framework, and database indexing.

Show enthusiasm for financial technology

Even if you do not have prior fintech experience, demonstrating an interest in wealth management systems and how technology drives financial services will make a positive impression.

During your interviews, be prepared for varying levels of interviewer engagement

If an interviewer seems brief or unengaged, remain professional, structured, and enthusiastic in your responses. Your consistency and composure are key parts of your evaluation.

Questions & practice

How do you manage your time and prioritize tasks when working on multiple concurrent engineering initiatives?

Medium · Behavioral & Collaboration

Approach

Say what the runtime actually does before reasoning about the code.
Name what is shared across threads and what owns each piece of state.
Identify the window where an invariant is briefly untrue.
Distinguish a value from a reference to it, and say which one you handed out.

Follow-up

What happens if two callers reach this at the same time?
Where could this allocate more than you expect?

Find overlapping job attempts and peak concurrency from lease records

Medium · sweep line · intervals · leases

A day of job_run history yields about 50,000,000 attempt records: (job_run_id, job_type, attempt, started_at, finished_at which is NULL when the worker died, lease_expires_at). Leases expire on a clock, so a job that outran its lease ran twice. Produce (a) every job_run_id whose attempts overlapped in wall-clock time and (b) the peak number of simultaneously running attempts per job_type with the minute it occurred. Target O(n log n). State how you treat a NULL finished_at and what clock skew does to your answer.

Approach

Define the interval before sorting anything: an attempt occupies [started_at, COALESCE(finished_at, lease_expires_at)). finished_at is observed and lease_expires_at is only a promise, so every attempt without a finish contributes an estimate and the whole result is a lower bound on overlap rather than an exact count.
For peak concurrency, sweep: emit 2n endpoints, sort by (timestamp, kind) with ends ordered before starts at equal timestamps, then walk the sequence maintaining a counter per job_type and record each type's maximum with its timestamp. O(n log n) dominated by the sort, O(n) space, or O(1) extra if the sort is external and the walk streams.
For overlap detection, do not compare attempts pairwise. A single global sort by (job_run_id, started_at) gives both the grouping and the order; within a group, keep the maximum end seen so far and report an overlap exactly when the next start is less than that running maximum, which is one linear pass after the sort.
Half-open intervals matter and are easy to get wrong: with closed intervals an attempt ending at the same millisecond another begins reads as concurrency two, and across 50,000,000 records that artefact swamps the real signal.

Follow-up

A handler is not idempotent and you have found 400 overlapping jobs. Which of them actually caused damage, and what would you query to find out?
Peak concurrency for one job_type is 4 against a configured cap of 4. Is the cap working, or is the data hiding attempts that never started?

Track a rolling failure rate per destination for circuit decisions

Easy · sliding window · ring buffer · circuit breaker

The egress service delivers about 1,500 webhooks per second across roughly 40,000 destinations, each call bounded by a 10 second timeout. Maintain, per destination, the failure rate over the trailing 60 seconds so a caller can ask before dispatch whether the circuit should open. Attempts arrive as (destination_id, finished_at_ms, outcome). Requirement: amortised O(1) per attempt, with total memory bounded by the destination count rather than by traffic. Give the structure, its exact memory, and the rule that stops a destination with three attempts from opening a circuit.

Approach

Name the exact-deque version and then reject it as the default. Holding timestamps and advancing a tail pointer past anything older than now minus 60 seconds is a correct two-pointer window at amortised O(1) per attempt, but its memory tracks in-window traffic, so one destination in a retry storm holds hundreds of thousands of entries while thousands of quiet destinations hold none.
Use a ring of 60 one-second buckets per destination, each bucket a pair of counters for attempts and failures. On an attempt, advance the ring by the elapsed whole seconds, zeroing at most min(elapsed, 60) buckets, then increment the head. That is amortised O(1) with a fixed footprint per destination.
State the footprint: 60 buckets times two 4-byte counters is 480 bytes of payload per destination, so 40,000 destinations is roughly 20 to 25 MB with per-entry overhead, bounded by the catalogue rather than by the rate. The cost is granularity, since the oldest bucket ages out in whole seconds, which is far tighter than the decision needs.
Require a minimum sample before the circuit may open. A destination with three attempts and three failures reads as 100 percent and is not evidence; a floor of roughly 20 attempts in the window makes the ratio meaningful, and below that floor use a run of consecutive failures as the trigger instead.

Follow-up

The fleet is 30 instances and each sees roughly a thirtieth of a destination's traffic. Where does the rate actually live, and what does a per-instance answer get wrong?
A destination answers in 9.5 seconds and succeeds. It is not failing but it is consuming your per-destination concurrency. What signal should open the circuit here?

Explain your experience with database design, query optimization, and managing large datasets in a Microsoft S

Medium · Technical & Domain Knowledge

Explain your experience with database design, query optimization, and managing large datasets in a Microsoft SQL Server environment.

Approach

Name the grain you start from and join outward from it.
Check whether any join is one-to-many before aggregating, or the sums inflate.
Say which index the query would use, and what makes it unusable.
Handle the rows that do not match: that is usually the actual question.

Follow-up

How does the query change if that join becomes one-to-many?
What happens to this when the table is ten times larger?

Denormalise tenant onto revisions and backfill it live

Hard · denormalisation · online migration · backfill

resource_revision (revision_id, resource_id, version, actor_user_id, change_kind, patch, request_id, created_at) has 400M rows and no tenant column; tenant_id lives only on resource. Two reads need it: a tenant-scoped audit feed ordered by created_at DESC, and an offboarding purge. Both join back to resource today. Justify adding tenant_id to resource_revision against those two reads, name the anomaly the copy introduces and the constraint that prevents it, then give the ordered migration for a live table taking 1.2k writes/second — the lock each step takes, how the backfill is batched, and where each step stops being reversible. PostgreSQL 16.

Approach

Justify from the access path rather than from taste. Without the column, the audit feed either scans resource_revision by created_at and discards other tenants' rows, or resolves the tenant's resource_ids first and probes with them — both proportional to the tenant's whole history rather than to one page. With (tenant_id, created_at DESC, revision_id DESC) it is a seek that stops at 50 rows, and the purge becomes a ranged delete instead of a join.
Name the cost exactly: a second copy of a fact can disagree with the first. Make the disagreement unwritable rather than documented — add UNIQUE (resource_id, tenant_id) on resource so it can serve as a foreign-key target, then FOREIGN KEY (resource_id, tenant_id) REFERENCES resource (resource_id, tenant_id) on the revision table. A revision can then only ever carry its parent's tenant.
Step one, expand: ALTER TABLE resource_revision ADD COLUMN tenant_id BIGINT NULL, with no default, so it is a catalogue change and no rewrite. It still needs ACCESS EXCLUSIVE for an instant, and that instant queues behind the longest open transaction on the table while every later query queues behind it — set lock_timeout to 2s and retry rather than wait.
Step two, dual-write: deploy the writer that populates tenant_id on every new revision while reads still use the join. Reversible by redeploying the previous build, because nothing reads the column yet.

Follow-up

The backfill is half finished and a rollback is required. What state is the table in, and what does the previous build do with a half-populated column?
How do you verify the backfill actually finished, given rows are still being inserted while it runs?

What are some of the different enterprise applications you have developed, and what were your specific contrib

Medium · Career History & Technical Background

What are some of the different enterprise applications you have developed, and what were your specific contributions to those projects?

Approach

Clarify what is being asked and what a complete answer contains.
State your assumptions explicitly before working the problem.
Say what you would check first and why it is the highest-information step.
Work from the requirement backwards to the design.

Follow-up

What assumption would you test first?
How would you know your answer was wrong?

How do you approach learning a new business domain or complex application architecture when joining a new team

Medium · Career History & Technical Background

How do you approach learning a new business domain or complex application architecture when joining a new team?

Approach

Fix the scope first: who calls this, how often, and what they do when it fails.
Name the read and write paths separately; they rarely have the same bottleneck.
Choose a partition key and say what query it makes expensive.
State the consistency you need, and where you are willing to be stale.

Follow-up

What breaks first when traffic grows ten times?
How does this behave when that dependency is down for an hour?

How do you ensure data integrity and security when integrating multiple third-party applications?

Medium · Technical & Domain Knowledge

Approach

Say who the caller is and what they do when the call fails halfway.
Define the identity of a request so a retry cannot double-apply it.
Separate accepted, pending, failed and confirmed; they are different facts.
Design the error taxonomy before the success shape; callers branch on it.

Follow-up

What happens if the caller retries after a timeout?
How does a client discover it is on an old version of this contract?

What are the key differences between various architectural patterns, such as microservices and monolithic arch

Medium · Technical & Domain Knowledge

What are the key differences between various architectural patterns, such as microservices and monolithic architectures, and when would you choose one over the other?

Approach

Fix the scope first: who calls this, how often, and what they do when it fails.
Name the read and write paths separately; they rarely have the same bottleneck.
Choose a partition key and say what query it makes expensive.
State the consistency you need, and where you are willing to be stale.

Follow-up

What breaks first when traffic grows ten times?
How does this behave when that dependency is down for an hour?

Read latency spikes on a sixty-second sawtooth

Medium · cache stampede · single-flight · ttl

The cached listing read path serves about 14k reads/second at an 85% hit rate. p99 sits at 35 ms for 57 seconds, jumps to 900 ms for 3, and repeats. During each spike the primary shows several hundred identical listing queries starting within the same millisecond, all carrying one large tenant's id. Cache entries use a 60-second TTL. Give the mechanism, the ordered checks, the fix, and the correctness hazard your fix must not introduce.

Approach

Match the period to a configured number before theorising about load. A spike every 60 seconds against a 60-second TTL is an entry expiring, and you confirm it by correlating spike timestamps with the entry's write time rather than with the traffic curve. If the period had matched a cron or a GC interval instead, this is a different investigation.
Establish the concurrency of the miss. Several hundred identical queries in one millisecond means the miss path has no coalescing: every request that arrives between expiry and repopulation recomputes. The herd size is that key's arrival rate times its recompute time, so at 1.2k reads/second for the hot key and a 250 ms recompute you expect about 300 concurrent misses, which matches what is observed.
Add single-flight on the miss path so one caller per key recomputes under a short-lived lock while the rest wait for its result. Prefer stale-while-revalidate where the read tolerates it: return the expired value immediately and refresh asynchronously, which removes the latency spike rather than serialising it into a queue of waiters.
De-synchronise the keys. Write TTLs with jitter, for example 60 seconds plus or minus 10%, so a deploy or a mass invalidation does not align every key on the same second and turn a per-key herd into a fleet-wide one.

Follow-up

The same sawtooth appears on a key that is invalidated on write rather than expired. Is that the same bug?
How does your answer change if the recompute takes 4 seconds instead of 250 ms?

Suggested practice checklist

Built from the rounds and topics Janney Montgomery Scott candidates report.

Day 1 — Map the Janney Montgomery Scott loop

Write out the reported sequence: Recruiter Screen, Technical Screening, Onsite Interview.
For each round, write one sentence on what it is judging, from the description above, and mark the one you are least ready for.

Deliverable: A one-page map of the 3 reported rounds, with the weakest marked.

Day 2 — Work Phone Screen Interviews

Spend the session on Phone Screen Interviews, which Janney Montgomery Scott candidates report being tested on.
Write one worked example in Phone Screen Interviews and time yourself on it.

Deliverable: One timed worked example in Phone Screen Interviews.

Day 3 — Work HR Interviewing

Spend the session on HR Interviewing, which Janney Montgomery Scott candidates report being tested on.
Write one worked example in HR Interviewing and time yourself on it.

Deliverable: One timed worked example in HR Interviewing.

Day 4 — Work Hiring Manager Technical Interview

Spend the session on Hiring Manager Technical Interview, which Janney Montgomery Scott candidates report being tested on.
Write one worked example in Hiring Manager Technical Interview and time yourself on it.

Deliverable: One timed worked example in Hiring Manager Technical Interview.

Day 5 — Answer out loud: Career History & Technical Background

Answer aloud, timed: Can you walk me through your employment history and highlight your experience with the Microsoft technology stack?
Answer aloud, timed: What are some of the different enterprise applications you have developed, and what were your specific contributions to those projects?

Deliverable: Spoken answers to 2 reported Career History & Technical Background question(s), under time.

Day 6 — Answer out loud: Technical & Domain Knowledge

Answer aloud, timed: How do you ensure data integrity and security when integrating multiple third-party applications?
Answer aloud, timed: What are the key differences between various architectural patterns, such as microservices and monolithic architectures, and when would you choose one over the other?

Deliverable: Spoken answers to 2 reported Technical & Domain Knowledge question(s), under time.

Day 7 — Answer out loud: Behavioral & Collaboration

Answer aloud, timed: Describe a situation where you had to work with an unengaged stakeholder or team member. How did you ensure the project's success?
Answer aloud, timed: How do you handle constructive feedback on your code during peer reviews?

Deliverable: Spoken answers to 2 reported Behavioral & Collaboration question(s), under time.

Behavioural preparation

Behavioural rounds judge the decision you made and what it cost.

Can you walk me through your employment history and highlight your experience with the Microsoft technology st

Medium · Career History & Technical Background

Can you walk me through your employment history and highlight your experience with the Microsoft technology stack?

Approach

Pick a story where you made the decision, not one where you watched it.
State the situation in two sentences and spend the rest on the reasoning.
Give the blast radius: what could have broken, and what you measured.
Name the disagreement and how you resolved it with evidence.

Follow-up

What would you do differently if you ran that again?
How did you know your change caused the improvement?

Describe a time when you had to optimize a slow-performing legacy application. What was your process?

Medium · Career History & Technical Background

Approach

Pick a story where you made the decision, not one where you watched it.
State the situation in two sentences and spend the rest on the reasoning.
Give the blast radius: what could have broken, and what you measured.
Name the disagreement and how you resolved it with evidence.

Follow-up

What would you do differently if you ran that again?
How did you know your change caused the improvement?

How do you handle exception handling and logging in a distributed enterprise application?

Medium · Technical & Domain Knowledge

Approach

Pick a story where you made the decision, not one where you watched it.
State the situation in two sentences and spend the rest on the reasoning.
Give the blast radius: what could have broken, and what you measured.
Name the disagreement and how you resolved it with evidence.

Follow-up

What would you do differently if you ran that again?
How did you know your change caused the improvement?

Describe a situation where you had to work with an unengaged stakeholder or team member. How did you ensure th

Medium · Behavioral & Collaboration

Describe a situation where you had to work with an unengaged stakeholder or team member. How did you ensure the project's success?

Approach

Pick a story where you made the decision, not one where you watched it.
State the situation in two sentences and spend the rest on the reasoning.
Give the blast radius: what could have broken, and what you measured.
Name the disagreement and how you resolved it with evidence.

Follow-up

What would you do differently if you ran that again?
How did you know your change caused the improvement?

How do you handle constructive feedback on your code during peer reviews?

Medium · Behavioral & Collaboration

Approach

Pick a story where you made the decision, not one where you watched it.
State the situation in two sentences and spend the rest on the reasoning.
Give the blast radius: what could have broken, and what you measured.
Name the disagreement and how you resolved it with evidence.

Follow-up

What would you do differently if you ran that again?
How did you know your change caused the improvement?

Tell me about a time when you had to explain a complex technical concept to a non-technical business partner.

Medium · Behavioral & Collaboration

Approach

Pick a story where you made the decision, not one where you watched it.
State the situation in two sentences and spend the rest on the reasoning.
Give the blast radius: what could have broken, and what you measured.
Name the disagreement and how you resolved it with evidence.

Follow-up

What would you do differently if you ran that again?
How did you know your change caused the improvement?